Test phpstan /w restricted php.ini conf

[mvorisek]

test #4147 and also disabled proc_open (which imply no parallelization possible)

probably no need to run full phpstan with these configurations

[mvorisek]

@ondrejmirtes test should be working, but for some reasons, the original code is run

[ondrejmirtes]

You get a nice error message:

In Process.php line 118:

  The Process class relies on proc_open(), which is not available on your PHP
   installation.

This behaviour is expected. There's no reason to disable these functions in the environment where you want to run PHPStan.

[mvorisek]

No, it the "detect CPU cores" code already account for that and it was working. But it was broken with some recent release.

In some environments, exec (and friends) functions can be disabled and phpstan should continue to work (using 1 process only).

[mvorisek]

@ondrejmirtes please reopen this PR, I will try to fix the issue, it worked before and phpstan should continue to work /w that php.ini configuration

[ondrejmirtes]

You can send a PR with a fix to phpstan-src and link this closed PR once you think it works.