Add a link-tot-paladin configuration

This CL adds a cbuildbot configuration, suitable for running in the
commit queue, which runs a build of ToT rather than of the manifest
under test. This is accomplished by adding a builder config attribute
'do_not_apply_cq_patches', and using MasterSlaveSyncStage instead of
CommitQueueSyncStage for paladin builders when this attribute is set
to True.

The new builder config builds against link, which we can eventually run
HWTest stage against.

BUG=chromium:323293
TEST=local cbuildbot build with --buildbot --debug, worked (failed
VMTest, but this is due to the specific ethernet configuration of my
Z620).

Change-Id: I0400e2a14d25a475b8d477f972f541802d3fed79
Reviewed-on: https://chromium-review.googlesource.com/177940
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index a901f72..a177215 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -576,7 +576,10 @@
       self.completion_stage_class = stages.PreCQCompletionStage
       self.patch_pool.gerrit_patches = []
     elif cbuildbot_config.IsCQType(self.build_config['build_type']):
-      sync_stage = self._GetStageInstance(stages.CommitQueueSyncStage)
+      if self.build_config['do_not_apply_cq_patches']:
+        sync_stage = self._GetStageInstance(stages.MasterSlaveSyncStage)
+      else:
+        sync_stage = self._GetStageInstance(stages.CommitQueueSyncStage)
       self.completion_stage_class = stages.CommitQueueCompletionStage
     elif cbuildbot_config.IsPFQType(self.build_config['build_type']):
       sync_stage = self._GetStageInstance(stages.MasterSlaveSyncStage)