fix _ALL_SOURCE logic to avoid possible redefinition of _GNU_SOURCE

this could be an error if _GNU_SOURCE was already defined differently
by the application.

diff --git a/include/features.h b/include/features.h
index 294c61dd6056eade62e2342dd44f7592fe0a303a..61ad2f5bc278a20ed0ed4c9a34af1cf01b8eb0ec 100644 (file)
--- a/include/features.h
+++ b/include/features.h
@@ -1,7 +1,7 @@
 #ifndef _FEATURES_H
 #define _FEATURES_H
 
-#ifdef _ALL_SOURCE
+#if defined(_ALL_SOURCE) && !defined(_GNU_SOURCE)
 #define _GNU_SOURCE 1
 #endif