Remove configure switch --disable-strong-random

This removes a portion of infrastructure introduced by fe0a0b5 to allow
compilation of Postgres in environments where no strong random source is
available, meaning that there is no linking to OpenSSL and no
/dev/urandom (Windows having its own CryptoAPI).  No systems shipped
this century lack /dev/urandom, and the buildfarm is actually not
testing this switch at all, so just remove it.  This simplifies
particularly some backend code which included a fallback implementation
using shared memory, and removes a set of alternate regression output
files from pgcrypto.

Author: Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20181230063219.GG608@paquier.xyz

Author: michaelpq

configure

@@ -761,7 +761,6 @@ GENHTML
 LCOV
 GCOV
 enable_debug
-enable_strong_random
 enable_rpath
 default_port
 WANTED_LANGUAGES
@@ -829,7 +828,6 @@ with_pgport
 enable_rpath
 enable_spinlocks
 enable_atomics
-enable_strong_random
 enable_debug
 enable_profiling
 enable_coverage
@@ -1512,7 +1510,6 @@ Optional Features:
                           executables
   --disable-spinlocks     do not use spinlocks
   --disable-atomics       do not use atomic operations
-  --disable-strong-random do not use a strong random number source
   --enable-debug          build with debugging symbols (-g)
   --enable-profiling      build with profiling enabled
   --enable-coverage       build with coverage testing instrumentation
@@ -3272,34 +3269,6 @@ fi
 
 
 
-#
-# Random number generation
-#
-
-
-# Check whether --enable-strong-random was given.
-if test "${enable_strong_random+set}" = set; then :
-  enableval=$enable_strong_random;
-  case $enableval in
-    yes)
-      :
-      ;;
-    no)
-      :
-      ;;
-    *)
-      as_fn_error $? "no argument expected for --enable-strong-random option" "$LINENO" 5
-      ;;
-  esac
-
-else
-  enable_strong_random=yes
-
-fi
-
-
-
-
 #
 # --enable-debug adds -g to compiler flags
 #
@@ -17937,7 +17906,7 @@ fi
 # in the template or configure command line.
 
 # If not selected manually, try to select a source automatically.
-if test "$enable_strong_random" = "yes" && test x"$USE_OPENSSL_RANDOM" = x"" && test x"$USE_WIN32_RANDOM" = x"" && test x"$USE_DEV_URANDOM" = x"" ; then
+if test x"$USE_OPENSSL_RANDOM" = x"" && test x"$USE_WIN32_RANDOM" = x"" && test x"$USE_DEV_URANDOM" = x"" ; then
   if test x"$with_openssl" = x"yes" ; then
     USE_OPENSSL_RANDOM=1
   elif test "$PORTNAME" = "win32" ; then
@@ -17971,42 +17940,28 @@ fi
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking which random number source to use" >&5
 $as_echo_n "checking which random number source to use... " >&6; }
-if test "$enable_strong_random" = yes ; then
-  if test x"$USE_OPENSSL_RANDOM" = x"1" ; then
+if test x"$USE_OPENSSL_RANDOM" = x"1" ; then
 
 $as_echo "#define USE_OPENSSL_RANDOM 1" >>confdefs.h
 
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: OpenSSL" >&5
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: OpenSSL" >&5
 $as_echo "OpenSSL" >&6; }
-  elif test x"$USE_WIN32_RANDOM" = x"1" ; then
+elif test x"$USE_WIN32_RANDOM" = x"1" ; then
 
 $as_echo "#define USE_WIN32_RANDOM 1" >>confdefs.h
 
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: Windows native" >&5
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: Windows native" >&5
 $as_echo "Windows native" >&6; }
-  elif test x"$USE_DEV_URANDOM" = x"1" ; then
+elif test x"$USE_DEV_URANDOM" = x"1" ; then
 
 $as_echo "#define USE_DEV_URANDOM 1" >>confdefs.h
 
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: /dev/urandom" >&5
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: /dev/urandom" >&5
 $as_echo "/dev/urandom" >&6; }
-  else
-    as_fn_error $? "
-no source of strong random numbers was found
-PostgreSQL can use OpenSSL or /dev/urandom as a source of random numbers,
-for authentication protocols. You can use --disable-strong-random to use a
-built-in pseudo random number generator, but that may be insecure." "$LINENO" 5
-  fi
-
-$as_echo "#define HAVE_STRONG_RANDOM 1" >>confdefs.h
-
 else
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: weak builtin PRNG" >&5
-$as_echo "weak builtin PRNG" >&6; }
-    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING:
-*** Not using a strong random number source may be insecure." >&5
-$as_echo "$as_me: WARNING:
-*** Not using a strong random number source may be insecure." >&2;}
+  as_fn_error $? "
+no source of strong random numbers was found
+PostgreSQL can use OpenSSL or /dev/urandom as a source of random numbers." "$LINENO" 5
 fi
 
 # If not set in template file, set bytes to use libc memset()

configure.in

@@ -193,13 +193,6 @@ PGAC_ARG_BOOL(enable, spinlocks, yes,
 PGAC_ARG_BOOL(enable, atomics, yes,
               [do not use atomic operations])
 
-#
-# Random number generation
-#
-PGAC_ARG_BOOL(enable, strong-random, yes,
-              [do not use a strong random number source])
-AC_SUBST(enable_strong_random)
-
 #
 # --enable-debug adds -g to compiler flags
 #
@@ -2151,7 +2144,7 @@ fi
 # in the template or configure command line.
 
 # If not selected manually, try to select a source automatically.
-if test "$enable_strong_random" = "yes" && test x"$USE_OPENSSL_RANDOM" = x"" && test x"$USE_WIN32_RANDOM" = x"" && test x"$USE_DEV_URANDOM" = x"" ; then
+if test x"$USE_OPENSSL_RANDOM" = x"" && test x"$USE_WIN32_RANDOM" = x"" && test x"$USE_DEV_URANDOM" = x"" ; then
   if test x"$with_openssl" = x"yes" ; then
     USE_OPENSSL_RANDOM=1
   elif test "$PORTNAME" = "win32" ; then
@@ -2166,28 +2159,19 @@ if test "$enable_strong_random" = "yes" && test x"$USE_OPENSSL_RANDOM" = x"" &&
 fi
 
 AC_MSG_CHECKING([which random number source to use])
-if test "$enable_strong_random" = yes ; then
-  if test x"$USE_OPENSSL_RANDOM" = x"1" ; then
-    AC_DEFINE(USE_OPENSSL_RANDOM, 1, [Define to use OpenSSL for random number generation])
-    AC_MSG_RESULT([OpenSSL])
-  elif test x"$USE_WIN32_RANDOM" = x"1" ; then
-    AC_DEFINE(USE_WIN32_RANDOM, 1, [Define to use native Windows API for random number generation])
-    AC_MSG_RESULT([Windows native])
-  elif test x"$USE_DEV_URANDOM" = x"1" ; then
-    AC_DEFINE(USE_DEV_URANDOM, 1, [Define to use /dev/urandom for random number generation])
-    AC_MSG_RESULT([/dev/urandom])
-  else
-    AC_MSG_ERROR([
-no source of strong random numbers was found
-PostgreSQL can use OpenSSL or /dev/urandom as a source of random numbers,
-for authentication protocols. You can use --disable-strong-random to use a
-built-in pseudo random number generator, but that may be insecure.])
-  fi
-  AC_DEFINE(HAVE_STRONG_RANDOM, 1, [Define to use have a strong random number source])
+if test x"$USE_OPENSSL_RANDOM" = x"1" ; then
+  AC_DEFINE(USE_OPENSSL_RANDOM, 1, [Define to use OpenSSL for random number generation])
+  AC_MSG_RESULT([OpenSSL])
+elif test x"$USE_WIN32_RANDOM" = x"1" ; then
+  AC_DEFINE(USE_WIN32_RANDOM, 1, [Define to use native Windows API for random number generation])
+  AC_MSG_RESULT([Windows native])
+elif test x"$USE_DEV_URANDOM" = x"1" ; then
+  AC_DEFINE(USE_DEV_URANDOM, 1, [Define to use /dev/urandom for random number generation])
+  AC_MSG_RESULT([/dev/urandom])
 else
-    AC_MSG_RESULT([weak builtin PRNG])
-    AC_MSG_WARN([
-*** Not using a strong random number source may be insecure.])
+  AC_MSG_ERROR([
+no source of strong random numbers was found
+PostgreSQL can use OpenSSL or /dev/urandom as a source of random numbers.])
 fi
 
 # If not set in template file, set bytes to use libc memset()