Fix m4 quotation

nikic · nikic · commit 05478e985eb5 · 2020-08-08T10:38:51.000+02:00
We should not try to expand AX_CHECK_COMPILE_FLAG inside the
error message...
diff --git a/build/php.m4 b/build/php.m4
@@ -305,7 +305,7 @@ fi
 ])
 
 AC_DEFUN([PHP_CHECK_GCC_ARG],[
-  AC_MSG_ERROR([Use AX_CHECK_COMPILE_FLAG instead])
+  AC_MSG_ERROR([[Use AX_CHECK_COMPILE_FLAG instead]])
 ])
 
 dnl
