Assume that we have rint().

Windows has this since _MSC_VER >= 1200, and so do all other live
platforms according to the buildfarm, so remove the configure probe
and src/port/ substitution.

This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code.  I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.

Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us

Author: tglsfdc

configure

@@ -15628,19 +15628,6 @@ esac
 
 fi
 
-ac_fn_c_check_func "$LINENO" "rint" "ac_cv_func_rint"
-if test "x$ac_cv_func_rint" = xyes; then :
-  $as_echo "#define HAVE_RINT 1" >>confdefs.h
-
-else
-  case " $LIBOBJS " in
-  *" rint.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS rint.$ac_objext"
- ;;
-esac
-
-fi
-
 ac_fn_c_check_func "$LINENO" "srandom" "ac_cv_func_srandom"
 if test "x$ac_cv_func_srandom" = xyes; then :
   $as_echo "#define HAVE_SRANDOM 1" >>confdefs.h

configure.in

@@ -1707,7 +1707,6 @@ AC_REPLACE_FUNCS(m4_normalize([
 	pread
 	pwrite
 	random
-	rint
 	srandom
 	strlcat
 	strlcpy

src/include/pg_config.h.in

@@ -451,9 +451,6 @@
 /* Define to 1 if you have the `readlink' function. */
 #undef HAVE_READLINK
 
-/* Define to 1 if you have the `rint' function. */
-#undef HAVE_RINT
-
 /* Define to 1 if you have the global variable
    'rl_completion_append_character'. */
 #undef HAVE_RL_COMPLETION_APPEND_CHARACTER

src/include/port.h

@@ -385,10 +385,6 @@ extern float pg_strtof(const char *nptr, char **endptr);
 extern char *mkdtemp(char *path);
 #endif
 
-#ifndef HAVE_RINT
-extern double rint(double x);
-#endif
-
 #ifndef HAVE_INET_ATON
 #include <netinet/in.h>
 #include <arpa/inet.h>

src/port/rint.c

@@ -104,8 +104,6 @@ sub mkvcbuild
 	  sprompt.c strerror.c tar.c thread.c
 	  win32env.c win32error.c win32security.c win32setlocale.c);
 
-	push(@pgportfiles, 'rint.c') if ($vsVersion < '12.00');
-
 	push(@pgportfiles, 'strtof.c') if ($vsVersion < '14.00');
 
 	if ($vsVersion >= '9.00')

src/tools/msvc/Mkvcbuild.pm

@@ -321,7 +321,6 @@ sub GenerateFiles
 		HAVE_READLINE_HISTORY_H     => undef,
 		HAVE_READLINE_READLINE_H    => undef,
 		HAVE_READLINK               => undef,
-		HAVE_RINT                   => 1,
 		HAVE_RL_COMPLETION_APPEND_CHARACTER      => undef,
 		HAVE_RL_COMPLETION_MATCHES               => undef,
 		HAVE_RL_COMPLETION_SUPPRESS_QUOTE        => undef,