gitweb: Change parse_commits signature to allow for multiple options

gitweb: Change parse_commits signature to allow for multiple options

Change order of parameters in parse_commits() to have $filename
before @args (extra options), to allow for multiple extra options,
for example both '--grep=<pattern>' and '--fixed-strings'.

Change all callers to follow new calling convention.

Originally by Petr Baudis, in http://repo.or.cz/git/gitweb.git:

    b98f0a7c gitweb: Clearly distinguish regexp / exact match searches

Signed-off-by: Petr Baudis <redacted>
Signed-off-by: Jakub Narebski <redacted>
Signed-off-by: Junio C Hamano <redacted>