cleanups: ensure that git-compat-util.h is included first

CodingGuidelines states that the first #include in C files should be
git-compat-util.h or another header file that includes it, such as
cache.h or builtin.h.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

test-regex.c

@@ -1,4 +1,4 @@
-#include <git-compat-util.h>
+#include "git-compat-util.h"
 
 int main(int argc, char **argv)
 {