add: free leaked pathspec after add_files_to_cache()

After run_diff_files, we throw away the rev_info struct,
including the pathspec that we copied into it, leaking the
memory. this is probably not a big deal in practice. We
usually only run this once per process, and the leak is
proportional to the pathspec list we're already holding in
memory.

But it's still a leak, and it pollutes leak-checker output,
making it harder to find important leaks.

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

builtin/add.c

@@ -119,6 +119,7 @@ int add_files_to_cache(const char *prefix,
 	rev.diffopt.flags |= DIFF_OPT_OVERRIDE_SUBMODULE_CONFIG;
 	rev.max_count = 0; /* do not compare unmerged paths with stage #2 */
 	run_diff_files(&rev, DIFF_RACY_IS_MODIFIED);
+	clear_pathspec(&rev.prune_data);
 	return !!data.add_errors;
 }