[Minor] Fix build on some systems

diff --git a/contrib/backward-cpp/backward.hpp b/contrib/backward-cpp/backward.hpp
index b853f8308a7b6c5a96350c9742d545704b55acbd..ce725559b6a0a767d3fb8ca13a8baae9dd55b7d1 100644 (file)
--- a/contrib/backward-cpp/backward.hpp
+++ b/contrib/backward-cpp/backward.hpp
@@ -379,7 +379,13 @@ typedef SSIZE_T ssize_t;
 
 #if BACKWARD_HAS_UNWIND == 1
 
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#include <unwind.h>
+#undef _GNU_SOURCE
+#else
 #include <unwind.h>
+#endif
 // while gcc's unwind.h defines something like that:
 //  extern _Unwind_Ptr _Unwind_GetIP (struct _Unwind_Context *);
 //  extern _Unwind_Ptr _Unwind_GetIPInfo (struct _Unwind_Context *, int *);