Use GitHooks to make sure that tools/make-toolchain.sh is executed on each branch switch

[sy2002]

@MJoergen and @bernd-ulmann It happens frequently to me, that when I am switching branches that I am forgetting to re-run tools/make-toolchain.sh. The results of failing to remember this each time are ranging from "nothing bad happened" to complete desasters (which eat a ton of time to resolve) like black VGA screens after synthesis due to not-recompiled Monitor and PORE.

So I wondered: Is there a way to force some scripts to be run, each time you switch branches? The answer seems to be yes, so I assigned this task to me

https://stackoverflow.com/questions/1011557/is-there-a-way-to-trigger-a-hook-after-a-new-branch-has-been-checked-out-in-git