Move scm.py to lib/

It belongs there.

Change-Id: I286b50c43c587c39557fc508175efbd4b0f51d51
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4289680
Reviewed-by: Joanna Wang <jojwang@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
diff --git a/split_cl.py b/split_cl.py
index 433352f..54fd4c1 100644
--- a/split_cl.py
+++ b/split_cl.py
@@ -16,7 +16,7 @@
 
 import gclient_utils
 import git_footers
-import scm
+from lib import scm
 
 import git_common as git