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/gclient_scm.py b/gclient_scm.py
index 3b1b59f..e94a2f4 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -28,7 +28,7 @@
 import gclient_utils
 import gerrit_util
 import git_cache
-import scm
+from lib import scm
 import shutil
 import subprocess2