Actually, option available from gcc 4.9

src/civetweb.c

@@ -19046,7 +19046,7 @@ mg_get_system_info_impl(char *buffer, int buflen)
 	/* Build date */
 	{
 #if defined(GCC_DIAGNOSTIC)
-#if GCC_VERSION >= 50000
+#if GCC_VERSION >= 40900
 #pragma GCC diagnostic push
 /* Disable bogus compiler warning -Wdate-time, appeared in gcc5 */
 #pragma GCC diagnostic ignored "-Wdate-time"
@@ -19061,7 +19061,7 @@ mg_get_system_info_impl(char *buffer, int buflen)
 		            eol);
 
 #if defined(GCC_DIAGNOSTIC)
-#if GCC_VERSION >= 50000
+#if GCC_VERSION >= 40900
 #pragma GCC diagnostic pop
 #endif
 #endif