Revert "Build PHP by version, not by final target repository"

Summary:
Some PHP options, like the path where files should be installed
are set during the build step. As such, each build needs its
own directory.

This reverts commit fc0560fee018f820910d3fcadc9c72a1ed2d5781.

Ref T1469

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1469

Differential Revision: https://devcentral.nasqueron.org/D1940