Added Makefile for the buildbot

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added wrapper script to execute Graal version more conveniently

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added file defining the graal version to be used

- useful to trigger recompilation and benchmarking
- updated to latest Graal upstream version

Signed-off-by: Stefan Marr <git@stefan-marr.de>