GEARRT: update grackle
- update the grackle API for newer version of grackle
- includes minor other fixes
- I spent waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaay to much time trying to get autoconf to somehow check for the correct grackle version being installed by explicitly checking the grackle version. Can't get it to work. So now I'm checking for 2 specific new functions in the grackle API, and hoping that will catch most issues with deprecated grackle versions.