Improve Salt-controlled PHP build process

Summary:
The creates values are improved, as ./configure is actually
provided in the PHP distribution tarball.

Allow make to really occur in the build directory, and not
in the Salt home directory, as the cd command was independantly
run before the make one.

Test Plan: build PHP 5.6.40 on Ysul

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2085