store git hash also in xlf-info message of gauge and propagator files

[urbach]

currently there is only the hmc version, but not the git hash. This is currently quite missleading.

We should also increase the version soon...

[kostrzewa]

I wanted to implement this a while ago but I became confused by how the xlf-info was constructed. One thing that I remember is that the git-hash needs to be passed through as a function parameter, otherwise, because git-hash.h is built dynamically and defines a constant, things become a bit confusing to the linker.

[urbach]

yes, the compilers keep complaining about the git-hash being a constant...

[deuzeman]

I think I wrote this code originally, so I can have a look.