git p4 test: ensure p4 symlink parsing works

git p4 test: ensure p4 symlink parsing works

While this happens to work, there was no test to make sure
that the basic importing of a symlink from p4 to git functioned.

Add a simple test to create a symlink in p4 and import it into git,
then verify that the symlink exists and has the correct target.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>