Http tests fails on Debian with Apache 2.4

Http tests fails on Debian with Apache 2.4
https://bugs.webkit.org/show_bug.cgi?id=120352

Reviewed by Andreas Kling.

Tools:

Select httpd.conf file for debian based on version, matching Fedora behavior.

* Scripts/webkitpy/port/base.py:
(Port._apache_config_file_name_for_platform):

LayoutTests:

Added an apache 2.4 configuration file adapted from Fedora's,
and renamed the 2.2 file to have consistent naming.

* http/conf/debian-httpd-2.2.conf: Renamed from LayoutTests/http/conf/apache2-debian-httpd.conf.
* http/conf/debian-httpd-2.4.conf: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@154736 268f45cc-cd09-0410-ab3c-d52691b4dbfc