Paul Jakma:

lib/debug.{c,h}: glibc backtrace printing function (from the glibc info page)
configure.ac: check for glibc backtrace and set define
lib/zebra.h: glibc backtrace support
diff --git a/lib/zebra.h b/lib/zebra.h
index 7b1e801..62566cf 100644
--- a/lib/zebra.h
+++ b/lib/zebra.h
@@ -172,6 +172,10 @@
 #include <libutil.h>
 #endif /* HAVE_LIBUTIL_H */
 
+#ifdef HAVE_GLIBC_BACKTRACE
+#include <execinfo.h>
+#endif /* HAVE_GLIBC_BACKTRACE */
+
 #ifdef BSDI_NRL
 
 #ifdef HAVE_NETINET6_IN6_H