The --purify flag can now be passed to remove the temporary
files and directories created while building the iOS Framework or static
library. That way, only the final result(s) are taking up space in the
output folder.
BUG=None
NOTRY=True
Review-Url: https://codereview.webrtc.org/2740923003
Cr-Commit-Position: refs/heads/master@{#17224}