Allow PHP to be built by builder user

Summary:
Currently, a parameter error makes PHP be built as root.

This change enables the less privileged build process
to actually work.

This is a follow-up for d07877e8.

Test Plan: salt-call --local state.sls roles/webserver-legacy/php-builder

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2092