[question] ZTS version of php

Is it possible to get PHP-ZTS (Zend Thread Safe, compilation flag, allows installing `parallel` extension) with asdf-php? Even if this would mean I need to locally build it (just want to have asdf goodies such as .tool-version file).

I need it when working with [react php](https://github.com/reactphp/reactphp) with [parallel library](https://github.com/reactphp-parallel/reactphp-parallel) - the parallel extension cannot work with non-thread safe build of PHP.

Note: im not asking for default to be ZTS. Most people don't need ZTS and it comes at performence cost

Start by reviewing the asdf-php plugin's PHP build entry points and how .tool-version is handled. Check whether a local ZTS build can be represented without changing the default non-thread-safe build; done means a repeatable ZTS installation works with parallel while ordinary installs remain unchanged.

Written by the indexing model from the issue text.