updated tests for defining __FUNCTION__ (Dan Schikore)
diff --git a/src/mesa/main/glheader.h b/src/mesa/main/glheader.h
index 0ebadaa..e37499e 100644
--- a/src/mesa/main/glheader.h
+++ b/src/mesa/main/glheader.h
@@ -247,9 +247,12 @@
* Don't define it if using a newer Windows compiler.
*/
#if defined(__VMS)
-#define __FUNCTION__ "VMS$NL:"
-#elif !(defined(__GNUC__) && __GNUC__ >= 2) && !(defined(_MSC_VER) && _MSC_VER >= 1300)
-#define __FUNCTION__ "unknown"
+# define __FUNCTION__ "VMS$NL:"
+#elif __STDC_VERSION__ < 199901L
+# if ((!defined __GNUC__) || (__GNUC__ < 2)) && (!defined __xlC__) && \
+ (!defined(_MSC_VER) || _MSC_VER < 1300)
+# define __FUNCTION__ "<unknown>"
+# endif
#endif