b4073bb3 (git-p4: Do not include diff in spec file when just
preparing p4, 2014-05-24) broke git p4 submit, here is a proper
fix, including proper handling for windows end of lines.
Signed-off-by: Maxime Coste <frrrwww@gmail.com> Acked-by: Pete Wyckoff <pw@padd.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>