update-index: fix xgetcwd() related memory leak

As xgetcwd() returns an allocated buffer, we should free this
buffer when we don't need it any more.

This was found by Coverity.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: chriscool

builtin/update-index.c

@@ -125,12 +125,16 @@ static int test_if_untracked_cache_is_supported(void)
 	struct stat st;
 	struct stat_data base;
 	int fd, ret = 0;
+	char *cwd;
 
 	strbuf_addstr(&mtime_dir, "mtime-test-XXXXXX");
 	if (!mkdtemp(mtime_dir.buf))
 		die_errno("Could not make temporary directory");
 
-	fprintf(stderr, _("Testing mtime in '%s' "), xgetcwd());
+	cwd = xgetcwd();
+	fprintf(stderr, _("Testing mtime in '%s' "), cwd);
+	free(cwd);
+
 	atexit(remove_test_directory);
 	xstat_mtime_dir(&st);
 	fill_stat_data(&base, &st);