Add '.bak' for sed -i that is required by BSD sed

BSD version of sed requires a parameter for '-i' option.
Add '.bak' for back up and remove the back up file at the end of the
sed command

Bug: 112478836
Test: checkbuild on a mac machine
Merged-In: Iedc93c2b5239004d2bbb8011488041c54b29996b
Change-Id: Iedc93c2b5239004d2bbb8011488041c54b29996b
(cherry picked from commit 6009d874)