Fix PERMIT_DECLARATION_AFTER_STATEMENT initialization.

The defect caused a mere warning and only for gcc versions before 3.4.0.

Author: nmisch

configure

@@ -5306,7 +5306,7 @@ fi
   # -Wdeclaration-after-statement isn't applicable for C++.  Specific C files
   # disable it, so AC_SUBST the negative form.
   PERMIT_DECLARATION_AFTER_STATEMENT=
-  if test x"save_$CFLAGS" != x"$CFLAGS"; then
+  if test x"$save_CFLAGS" != x"$CFLAGS"; then
     PERMIT_DECLARATION_AFTER_STATEMENT=-Wno-declaration-after-statement
   fi
 

configure.in

@@ -481,7 +481,7 @@ if test "$GCC" = yes -a "$ICC" = no; then
   # -Wdeclaration-after-statement isn't applicable for C++.  Specific C files
   # disable it, so AC_SUBST the negative form.
   PERMIT_DECLARATION_AFTER_STATEMENT=
-  if test x"save_$CFLAGS" != x"$CFLAGS"; then
+  if test x"$save_CFLAGS" != x"$CFLAGS"; then
     PERMIT_DECLARATION_AFTER_STATEMENT=-Wno-declaration-after-statement
   fi
   AC_SUBST(PERMIT_DECLARATION_AFTER_STATEMENT)