Added Linux and Windows CI builds using GitHub Actions

[RICCIARDI-Adrien]

Windows build should also be easier even for developing purposes.

[TeslaRus]

try this AL internal, please https://github.com/TeslaRus/OpenTomb/tree/master/extern/al
it works on Linux and MinGW too

[RICCIARDI-Adrien]

OK.
What C files did you compile ? All the ones contained in al subdirectories ?
May I add a CMakeFiles.txt to al directory ?

[TeslaRus]

yes, all files
May I add a CMakeFiles.txt to al directory ? - ok )

[RICCIARDI-Adrien]

@TeslaRus, are you using MinGW on Cygwin ?
It seems that Windows threads have been removed from your OpenAL version, only pthreads are left.

[TeslaRus]

yes, mingw has pthreads library (cut version, but enough for AL)

[RICCIARDI-Adrien]

New OpenAL is now fully integrated. It is statically linked to avoid deploying one more DLL.

[vvs-]

I've just checked the result: OpenTomb repository size has doubled because of the Windows binaries. I think that was not a good idea, because git is really bad at handling binaries. I'd split those away or this blow up could become a problem with time.

[vvs-]

Reverted as per discussion in #600.