submodule.c: Squelch a "use before assignment" warning

i686-apple-darwin9-gcc-4.0.1 (GCC) 4.0.1 (Apple Inc. build 5493) compiler
(and probably others) mistakenly thinks variable 'right' is used
before assigned.  Work around it by giving it a fake initialization.

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

submodule.c

@@ -38,7 +38,7 @@ void show_submodule_summary(FILE *f, const char *path,
 		const char *del, const char *add, const char *reset)
 {
 	struct rev_info rev;
-	struct commit *commit, *left = left, *right;
+	struct commit *commit, *left = left, *right = right;
 	struct commit_list *merge_bases, *list;
 	const char *message = NULL;
 	struct strbuf sb = STRBUF_INIT;