git-p4: clean-up code style in tests

Preliminary clean-up of testing libraries for git-p4.

* spaces added to both sides of () in function definitions in lib-git-p4
* tab indentation added to git-p4 tests when <<- redirection is used

Signed-off-by: Jan Durovec <jan.durovec@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>