Fix #79895: support = in PHP_CHECK_GCC_ARG m4 macro

Closes GH-5890.

Author: smola

NEWS

@@ -6,6 +6,8 @@ PHP                                                                        NEWS
   . Fixed bug #79884 (PHP_CONFIG_FILE_PATH is meaningless). (cmb)
   . Fixed bug #77932 (File extensions are case-sensitive). (cmb)
   . Fixed bug #79806 (realpath() erroneously resolves link to link). (cmb)
+  . Fixed bug #79895 (PHP_CHECK_GCC_ARG does not allow flags with equal sign).
+    (Santiago M. Mola)
 
 - LDAP:
   . Fixed memory leaks. (ptomulik)

acinclude.m4

@@ -329,8 +329,8 @@ dnl
 dnl PHP_CHECK_GCC_ARG(arg, action-if-found, action-if-not-found)
 dnl
 AC_DEFUN([PHP_CHECK_GCC_ARG],[
-  gcc_arg_name=[ac_cv_gcc_arg]translit($1,A-Z-,a-z_)
-  AC_CACHE_CHECK([whether $CC supports $1], [ac_cv_gcc_arg]translit($1,A-Z-,a-z_), [
+  gcc_arg_name=[ac_cv_gcc_arg]translit($1,A-Z=-,a-z__)
+  AC_CACHE_CHECK([whether $CC supports $1], [ac_cv_gcc_arg]translit($1,A-Z=-,a-z__), [
   echo 'void somefunc() { };' > conftest.c
   cmd='$CC $1 -c conftest.c'
   if eval $cmd 2>&1 | $EGREP -e $1 >/dev/null ; then