Remove one odd rebuild to get build revision
Use git-describe instead of plain hash for version
Fix odd recompilation in Windows makefile

Same as for Automake before.
Extract update-compile-info script

This deduplicates code in Makefiles for different platforms.
Change "git hash/revision" to "git info"
Better update-compile-info script
Merge branch 'better-git-revision-update'

* Fix odd rebuild after revision change.
* Extract revision update to a script.
* Use `git describe` instead of raw hash.