build: parse git annotated tag version into major/minor

Otherwise that version will be old (like now, I just forgot to update
it after v0.2 was created)

And also as a note, in c57d618558e25bfd6e8e60fc2b5ba7e4703b3db2 the
version was broken and compilation of the version module too, because of
silly mistake: setting this version was moved into the macro and this
macro not called (this even mustn't be commited)