diff-highlight: ignore test cruft

These are the same as in the normal t/.gitignore, with the
exception of ".prove", as our Makefile does not support it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/contrib/diff-highlight/t/.gitignore b/contrib/diff-highlight/t/.gitignore
new file mode 100644
index 0000000..7dcbb23
--- /dev/null
+++ b/contrib/diff-highlight/t/.gitignore
@@ -0,0 +1,2 @@
+/trash directory*
+/test-results