Fix ini values not getting restored after request has finished

[manuelm]

This fixes two separate cases of ini values not getting restored:

• The max_memory_limit handler directly overwrites the global memory_limit value.
• The fpm sapi does not restore any ini values passed through fcgi environment (PHP_VALUE header).

Both cases should be passed through zend_alter_ini, so modified_ini_directives can keep track.

[iluuu1994]

The OnChangeMaxMemoryLimit part makes sense to me. I did not know per-host ini settings were a thing, and could change OnChangeMaxMemoryLimit after OnChangeMemoryLimit.

As for the FPM part, I'll let that review up to Jakub, as I don't know much about FPM.