Rename chromite.buildbot -> chromite.cbuildbot.

The cbuildbot script lives in a directory named buildbot. Which is a
bit confusing.

BUG=chromium:373277
TEST=Unitests + cros lint.
CQ-DEPEND=CL:200157
CQ-DEPEND=CL:200165
CQ-DEPEND=CL:200149
CQ-DEPEND=CL:*163598
CQ-DEPEND=CL:*163760
CQ-DEPEND=CL:*163786

Change-Id: Ia5953a4506e8b47d27e1a6908ecb938a439da8c2
Reviewed-on: https://chromium-review.googlesource.com/199664
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
diff --git a/scripts/autotest_quickmerge.py b/scripts/autotest_quickmerge.py
index 09542d7..df90908 100644
--- a/scripts/autotest_quickmerge.py
+++ b/scripts/autotest_quickmerge.py
@@ -17,8 +17,8 @@
 import sys
 from collections import namedtuple
 
-from chromite.buildbot import constants
-from chromite.buildbot import portage_utilities
+from chromite.cbuildbot import constants
+from chromite.cbuildbot import portage_utilities
 from chromite.lib import cros_build_lib
 from chromite.lib import git
 from chromite.lib import osutils