git-p4: add failing tests for case-folding p4d

When p4d runs on a case-folding OS, git-p4 can end up getting
very confused. This adds failing tests to demonstrate the problem.

Signed-off-by: Luke Diamand <luke@diamand.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-git-p4.sh

@@ -69,7 +69,7 @@ start_p4d() {
 	(
 		cd "$db" &&
 		{
-			p4d -q -p $P4DPORT &
+			p4d -q -p $P4DPORT "$@" &
 			echo $! >"$pidfile"
 		}
 	) &&