Fix FindPkgConfig.cmake for multi config generators.

[Neumann-A]

Context: https://cmake.org/cmake/help/latest/module/FindPkgConfig.html

Problem:
The FindPkgConfig module is not configuration aware. As such it will not work correctly with multi config generators.

Solution:
simply adjust the module to do two configuration aware calls and setup targets/variables accordingly.

[JackBoosY]

@Neumann-A I'm not familiar with pkgconfig, can you open a PR to solve this?

Thanks.

[Neumann-A]

that probably needs to be added to /scripts/buildsystems/cmake/FindPkgConfig.cmake and the path /scripts/buildsystems/cmake/ added to the module path within the toolchain. I don't see compilin argument to try and make a port out of it.