gitweb/gitweb.perl: remove use of qw(...) as parentheses

gitweb/gitweb.perl: remove use of qw(...) as parentheses

Using the qw(...) construct as implicit parentheses was deprecated in
perl 5.13.5. Change the relevant code in gitweb to not use the
deprecated construct. The offending code was introduced in 3562198b by
Jakub Narebski.

The issue is that perl will now warn about this:

    $ perl -wE 'for my $i qw(a b) { say $i }'
    Use of qw(...) as parentheses is deprecated at -e line 1.
    a
    b

This caused gitweb.perl to warn on perl 5.13.5 and above, and these
tests to fail on those perl versions:

    ./t9501-gitweb-standalone-http-status.sh           (Wstat: 256 Tests: 11 Failed: 10)
      Failed tests:  2-11
      Non-zero exit status: 1
    ./t9502-gitweb-standalone-parse-output.sh          (Wstat: 256 Tests: 10 Failed: 9)
      Failed tests:  2-10
      Non-zero exit status: 1

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
Acked-by: Jakub Narębski <redacted>
Signed-off-by: Junio C Hamano <redacted>