Update the version tag correctly

[xtracko]

Eacirc is self version aware - or should be. Make the file verison.h.in to update at every build phase, not just at config phase.

Currently if you run cmake's configure a current commit tag is propagated into version.h file. The if you do a new commit and try to rebuild eacirc, the version.h file is not updated so the previous commit tag is used. To get the correct commit tag (the tag from eacirc was build) you must run cmake's reconfigure.

Ps.: some CMake knowledge is needed.

[Bender250]

Getting more important with submodules. The cmake is working even less deterministic (I was not able to produce binary with correct current version tag).