Disable legacy behavior always_populate_raw_post_data

Summary:
According Phabricator, this configuration triggers a warning:

always_populate_raw_post_data = 1
display_errors = 1
display_startup_errors = 1
error_reporting = -1

Warning text:

Automatically populating $HTTP_RAW_POST_DATA is deprecated and
will be removed in a future version. To avoid this warning set
'always_populate_raw_post_data' to '-1' in php.ini and use the
php://input stream instead.

Phabricator has raised a setup issue about this since 2016-08-26.

Some Docker images build on the top of this one use raw post
data, like rDNOTIF. But they already use php://input.

So it's safe to disable this.

References:

• https://secure.phabricator.com/w/changelog/2016.35/
• https://secure.phabricator.com/T9235
• http://php.net/manual/en/ini.core.php

Fixes T1004.

Test Plan: Tested successfully on DevCentral.

Reviewers: Sandlayth, dereckson

Spies: Nasqueron Docker deployment squad

Tags: Docker images

Maniphest Tasks: T1004

Differential Revision: https://devcentral.nasqueron.org/D646