*: make sure zebra.h is always included first

zebra.h pulls in config.h, which results in fiddling with things like
__FILE_OFFSET_BITS. It must always be included first, in order to set
flags that influence the compiler via <features.h>.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/lib/workqueue.c b/lib/workqueue.c
index 9fc8931..b1a5d5b 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -21,7 +21,7 @@
  * 02111-1307, USA.  
  */
 
-#include <lib/zebra.h>
+#include <zebra.h>
 #include "thread.h"
 #include "memory.h"
 #include "workqueue.h"