runtime/cgo: fix darwin/arm build

Macro definition ordering.

Change-Id: I0def4702d19a21a68ffa52ea5b7c22578830c578
Reviewed-on: https://go-review.googlesource.com/6030Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

src/runtime/cgo/gcc_darwin_arm.c

@@ -9,11 +9,11 @@
 #include <sys/param.h>
 #include <unistd.h>
 
+#include "libcgo.h"
+
 #include <CoreFoundation/CFBundle.h>
 #include <CoreFoundation/CFString.h>
 
-#include "libcgo.h"
-
 #define magic (0xe696c4f4U)
 
 // inittls allocates a thread-local storage slot for g.