git: update for git 2.0

prefixcmp() and suffixcmp() have been remove, functionality is now
provided by starts_with() and ends_with(). Retrurn values have been
changed, so instead of just renaming we have to fix logic.
Everything else looks just fine.
diff --git a/ui-summary.c b/ui-summary.c
index df99ce1..3728c3e 100644
--- a/ui-summary.c
+++ b/ui-summary.c
@@ -116,7 +116,7 @@
 	if (!ref) {
 		resolved_base = realpath(base_dir, NULL);
 		resolved_full = realpath(full_path, NULL);
-		if (!resolved_base || !resolved_full || prefixcmp(resolved_full, resolved_base)) {
+		if (!resolved_base || !resolved_full || !starts_with(resolved_full, resolved_base)) {
 			free(full_path);
 			full_path = NULL;
 		}