Only define _GNU_SOURCE if it is not already defined.

diff --git a/include/event2/util.h b/include/event2/util.h
index d96c231b1f2a836b4b1a8e042791f63f9bd081c3..98c26b6136497f3c59d03f55cf08489ff3e780d4 100644 (file)
--- a/include/event2/util.h
+++ b/include/event2/util.h
@@ -57,7 +57,9 @@ extern "C" {
 #endif
 #include <stdarg.h>
 #ifdef _EVENT_HAVE_NETDB_H
+#if !defined(_GNU_SOURCE)
 #define _GNU_SOURCE
+#endif
 #include <netdb.h>
 #endif