This allows for building binaries against `go-php` without needing an accompanying version of the
PHP library. To build a static version of `go-php`, simply set `STATIC=true` as a Make flag, e.g.:
make docker-build STATIC=true
The resulting `go-php` library will be placed in `.build/env/GOPATH/pkg/...` by default, and can be
used directly, but using the Docker image as a build environment will also work.
This adds PHP 7.2.1 as a new target, and updates existing PHP versions to their latest numbers. Be
aware that PHP 7.2.x is as-of-yet untested -- and expected to be buggy.
Alex Palaistras