configure: Make sure that gcc is recent enough for building 64-bit code.

configure

@@ -3897,6 +3897,58 @@ rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
 
       enable_win16=${enable_win16:-yes}
     else
+      if test "x${GCC}" = "xyes"
+      then
+        { $as_echo "$as_me:$LINENO: checking whether $CC supports __builtin_ms_va_list" >&5
+$as_echo_n "checking whether $CC supports __builtin_ms_va_list... " >&6; }
+        cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <stdarg.h>
+int
+main ()
+{
+void func(__builtin_ms_va_list *args);
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  { $as_echo "$as_me:$LINENO: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
+                           { { $as_echo "$as_me:$LINENO: error: You need gcc >= 4.4 to build Wine as 64-bit." >&5
+$as_echo "$as_me: error: You need gcc >= 4.4 to build Wine as 64-bit." >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+      fi
       TARGETFLAGS="-m64"
 
     fi

configure.ac

@@ -139,6 +139,14 @@ case $host in
       AC_SUBST(TARGETFLAGS,"-m32")
       enable_win16=${enable_win16:-yes}
     else
+      if test "x${GCC}" = "xyes"
+      then
+        AC_MSG_CHECKING([whether $CC supports __builtin_ms_va_list])
+        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdarg.h>]], [[void func(__builtin_ms_va_list *args);]])],
+                          [AC_MSG_RESULT([yes])],
+                          [AC_MSG_RESULT([no])
+                           AC_MSG_ERROR([You need gcc >= 4.4 to build Wine as 64-bit.])])
+      fi
       AC_SUBST(TARGETFLAGS,"-m64")
     fi
     ;;