t5540-http-push.sh: avoid non-portable grep -P

t5540-http-push.sh: avoid non-portable grep -P

OS X's GNU grep does not support -P/--perl-regexp.

We use a basic RE instead, and simplify the pattern slightly by
replacing '+' with '*' so it can be more easily expressed using a basic
RE.  The important part of pattern, checking for a SHA-1 has suffix in
the successful PUT/MOVE operations, remains the same.  Also, a-z instead
of a-f was an obvious mistake in the original RE. Here are samples of
what we want to match:

127.0.0.1 - - [26/Feb/2009:22:38:13 +0000] "PUT /test_repo.git/objects/3e/a4fbb9e18a401a6463c595d08118fcb9fb7426_fab55116904c665a95438bcc78521444a7db6096 HTTP/1.1" 201 277
127.0.0.1 - - [26/Feb/2009:22:38:13 +0000] "MOVE /test_repo.git/objects/3e/a4fbb9e18a401a6463c595d08118fcb9fb7426_fab55116904c665a95438bcc78521444a7db6096 HTTP/1.1" 201 277

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>