ls-files and read-tree need core.filemode

ls-files.c and read-tree.c miss the default configuration, in
particular the filemode=false part.  The recent +x bit flip made me
notice that, because git-merge refused to merge anything saying that
git-pull.sh is not up to date.

Signed-off-by: Junio C Hamano <junkio@cox.net>

ls-files.c

@@ -570,6 +570,7 @@ int main(int argc, const char **argv)
 	prefix = setup_git_directory();
 	if (prefix)
 		prefix_offset = strlen(prefix);
+	git_config(git_default_config);
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];