repack: make parsed string options const-correct

When we use OPT_STRING to parse an option, we get back a
pointer into the argv array, which should be "const char *".
The compiler doesn't notice because it gets passed through a
"void *" in the option struct.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/repack.c

@@ -129,7 +129,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	/* variables to be filled by option parsing */
 	int pack_everything = 0;
 	int delete_redundant = 0;
-	char *unpack_unreachable = NULL;
+	const char *unpack_unreachable = NULL;
 	int window = 0, window_memory = 0;
 	int depth = 0;
 	int max_pack_size = 0;