Introduce clang-format

An automated and opinionated style for code. We can decide to change the
style and have the source updated by the clang-format tool by running:

    make format

I've based the style on the Google style with exceptions to better
match
the current source style.

Change-Id: I43f85c7d4ce02ca999805558b25fcab2e43859c6
diff --git a/inc/cpio.h b/inc/cpio.h
index cc244ce..a563ae6 100644
--- a/inc/cpio.h
+++ b/inc/cpio.h
@@ -16,7 +16,7 @@
 
 void cpio_init(struct cpio *c, const void *buf, size_t size);
 void cpio_init_iter(struct cpio *c, struct cpio_iter *iter);
-bool cpio_next(struct cpio_iter *iter, const char **name,
-	       const void **contents, size_t *size);
+bool cpio_next(struct cpio_iter *iter, const char **name, const void **contents,
+	       size_t *size);
 
-#endif  /* _CPIO_H */
+#endif /* _CPIO_H */