Blink LayoutTests: Enable directory indexes for Debian Apache 2.4.

The default Apache configuration (used on Windows, Mac, and unknown
Linux distributions) includes mod_autoindex, which generates directory
listings. These are very useful when running tests in a browser (or
content shell) via Tools/Scripts/run-blink-httpd, as they make it
possible to navigate to the desired test from the HTTP server's root,
instead of having to get the full path to a test in the browser's
address bar.

This CL updates the Debian configuration for Apache 2.4 to load
mod_autoindex, so Debian users can get the same directory listing that
is present on Windows and Mac. The CL also reorders some LoadModule
statements to bring the order closer to the default configuration. This
is intended to make it easier to compare the module lists in the future.

Tested by running third_party/WebKit/Tools/Scripts/run-blink-httpd on
Debian Testing.

Bug: 
Change-Id: I6ddf8fb53e3b91157ff8c544fb1844d0487c8276
Reviewed-on: https://chromium-review.googlesource.com/817767Reviewed-by: Jeff Carpenter <jeffcarp@chromium.org>
Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523627}

third_party/WebKit/Tools/Scripts/apache_config/debian-httpd-2.4.conf

@@ -21,16 +21,17 @@ LoadModule authz_core_module    modules/mod_authz_core.so
 LoadModule authz_host_module    modules/mod_authz_host.so
 LoadModule include_module       modules/mod_include.so
 LoadModule headers_module       modules/mod_headers.so
+LoadModule ssl_module           modules/mod_ssl.so
 LoadModule mime_module          modules/mod_mime.so
+LoadModule asis_module          modules/mod_asis.so
+LoadModule cgi_module           modules/mod_cgi.so
+LoadModule env_module           modules/mod_env.so
 LoadModule negotiation_module   modules/mod_negotiation.so
 LoadModule actions_module       modules/mod_actions.so
 LoadModule alias_module         modules/mod_alias.so
 LoadModule rewrite_module       modules/mod_rewrite.so
-LoadModule cgi_module           modules/mod_cgi.so
-LoadModule env_module           modules/mod_env.so
-LoadModule ssl_module           modules/mod_ssl.so
 Include /etc/apache2/mods-available/php*.load
-LoadModule asis_module          modules/mod_asis.so
+LoadModule autoindex_module     modules/mod_autoindex.so
 
 ServerName 127.0.0.1