Add php-spx extension

[LordSimal]

https://github.com/NoiseByNorthwest/php-spx is our preferred way of doing local profiling.

It would be awesome if this - also awesome - package would add support for that extension 😁

[crazywhalecc]

I tried to add spx, and it cannot be directly added in php-src embed building. There are too many imcompatible code and config in php-spx itself.

I'll check later in my spare time, we need to fix php-spx source first.

[LordSimal]

It was worth a try, thanks for checking.