When developing in the Android source tree, 'aidegen' can be used to
create an Intellij workspace. This also creates the file angle.iml in
the specified module directories, though, so this CL adds angle.iml to
ANGLE's .gitignore.
Bug: None
Change-Id: Id73380fa7750c591967aa81ec7a8c991e074a303
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2906104Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>
