build: Test for features.h and move include to lib/zebra.h
* configure.ac: Check for features.h, which is needed to get Clang to
define __STDC_IEC_559__.
* lib/{stream.c,zebra.h}: move the features.h include to zebra.h, so
lib/network.c also gets it.
diff --git a/lib/zebra.h b/lib/zebra.h
index 0ea5ee4..7c4adf1 100644
--- a/lib/zebra.h
+++ b/lib/zebra.h
@@ -94,6 +94,10 @@
#ifdef HAVE_STDBOOL_H
#include <stdbool.h>
#endif
+/* primarily for __STDC_IEC_559__ with clang */
+#ifdef HAVE_FEATURES_H
+#include <features.h>
+#endif
/* machine dependent includes */
#ifdef SUNOS_5