*: 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/isisd/topology/spgrid.c b/isisd/topology/spgrid.c
index 40147fb..22cfa7b 100644
--- a/isisd/topology/spgrid.c
+++ b/isisd/topology/spgrid.c
@@ -1,11 +1,11 @@
+#include <zebra.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "random.c"
 
-#include <zebra.h>
-
 #include "thread.h"
 #include "vty.h"
 #include "log.h"