Shader-compilation error-messages do not provide enough information

[JayFoxRox]

If XQEMU fails to compile / link a shader it currently only reports the compilation / link log (which is implementation dependent; Usually the line which caused the issue and a short message, but nothing else).
I think we should also include the complete set of shaders so it can be investigated more easily. This is also important because some drivers are very bad at generating a meaningful compilation / link log.
This will especially be helpful once we have users who will report bugs.
(A similar change was also done in Citra a while ago and it turned out to be useful)

The necessary changes should be done in hw/xbox/nv2a_shaders.c

Additionally we should probably dump the ShaderState to a file. That way we could more easily try to reproduce the error and also test proposed fixes without re-running the games. Such a tool could also be used in automated testing.
(We'll want a ShaderState dumper anyway so that we can generate commonly used shaders [from a database] at startup instead of runtime where it might cause microstutter)