Changes

Summary

1. Add LLVMGitPoller to listen for changes in the monorepo.
2. Separate automatic schedulers for builders depending on is_legacy_mode. Changes from SVN should be scheduled for builders which checkout from SVN, changes from github should be scheduled for builders which checkout from github. For a transition period we need the both types of schedulers. Patch by Andrei Lebedev. Differential Revision: https://reviews.llvm.org/D69159

Revision 375205 by gkistanova: Add LLVMGitPoller to listen for changes in the monorepo.
Change Type	Path in Repository	Path in Workspace
	/zorg/trunk/buildbot/osuosl/master/master.cfg	zorg/buildbot/osuosl/master/master.cfg
Revision 375204 by gkistanova: Separate automatic schedulers for builders depending on is_legacy_mode. Changes from SVN should be scheduled for builders which checkout from SVN, changes from github should be scheduled for builders which checkout from github. For a transition period we need the both types of schedulers. Patch by Andrei Lebedev. Differential Revision: https://reviews.llvm.org/D69159
Change Type	Path in Repository	Path in Workspace
	/zorg/trunk/buildbot/osuosl/master/config/schedulers.py	zorg/buildbot/osuosl/master/config/schedulers.py