tests: adjust the configuration for Apache 2.2

tests: adjust the configuration for Apache 2.2

Lars Schneider noticed that the configuration introduced to test the
extra HTTP headers cannot be used with Apache 2.2 (which is still
actively maintained, as pointed out by Junio Hamano).

To let the tests pass with Apache 2.2 again, let's substitute the
offending <RequireAll> and `expr` by using old school RewriteCond
statements.

As RewriteCond does not allow testing for *non*-matches, we simply match
the desired case first and let it pass by marking the RewriteRule as
'[L]' ("last rule, do not process any other matching RewriteRules after
this"), and then have another RewriteRule that matches all other cases
and lets them fail via '[F]' ("fail").

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Tested-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>