Fixing build problems due to endian.h

Have to define _DEFAULT_SOURCE before you can use the endian
conversion functions.  As most standard library headers use
features.h, and _DEFAULT_SOURCE must be defined before features.h is
included, we have to include base.h before other headers.

lib/inst.h

@@ -13,12 +13,12 @@
 #ifndef INST_H
 #define INST_H
 
-#include <stdio.h>
-#include <stdlib.h>
-
 #include <lib/base.h>
 #include <lib/darr.h>
 
+#include <stdio.h>
+#include <stdlib.h>
+
 typedef enum
 {
   OP_NOOP = 0,