Minijail: extract utility functions.

Extract utility functions and add them, together with logging,
to a separate util.(c|h) file.

BUG=chromium-os:33361
TEST=unit tests
TEST=security_Minijail0, security_Minijail_seccomp, platform_CrosDisksArchive.

Change-Id: Ied436a7b27f14ef87198b7bf007634b28cbbd480
Reviewed-on: https://gerrit.chromium.org/gerrit/29492
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Elly Jones <ellyjones@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Commit-Ready: Jorge Lucangeli Obes <jorgelo@chromium.org>
diff --git a/libminijail.c b/libminijail.c
index 13434f6..2c3d5b3 100644
--- a/libminijail.c
+++ b/libminijail.c
@@ -33,11 +33,10 @@
 #include <unistd.h>
 
 #include "libminijail.h"
-#include "libsyscalls.h"
 #include "libminijail-private.h"
-#include "logging.h"
 
 #include "syscall_filter.h"
+#include "util.h"
 
 /* Until these are reliably available in linux/prctl.h */
 #ifndef PR_SET_SECCOMP