Pre-check PIE deps with pkg-config

[asgrim]

From @krakjoe

is there any possibility to add pkg-config integration into the pie dependency resolver, it's quite typical for an extension to itself depend on some system/3rd party library, and the modern way extensions check for that library is with pkg-config ... we can't obviously actually install the dependencies (or maybe we could, I'm not sure), but we can at least detect why the build would fail before attempting it - often make output is confusing for people to read that are not used to reading make output, whereas "This build will fail because pkg-config says X" before make is ever invoked can't be missed/misunderstood

[asgrim]

Resolves #294

[asgrim]

Note: need to check if lib-<arbitrary-anything> can be specified in composer.json, or if it is limited

[theofidry]

Dunno if worth noting, PHPBrew uses prefix finders to configure the pkg-config

[asgrim]

Dunno if worth noting, PHPBrew uses prefix finders to configure the pkg-config

Definitely worth noting; I think we'll have to do something similar, as there are some libraries that don't provide pkg-config information (such as libbz2). First iteration I'll just roll out pkg-config support for now :)

[theofidry]

I'm not too familiar with it, but just in case, you can see there is also other providers, notably one for Homebrew.