Add option to ignore SIGINT when running DM on Android.

Bug: skia:6856
Change-Id: Iaaad2c22988cf8058304b7396c7d24eacd2f3edb
Reviewed-on: https://skia-review.googlesource.com/24745
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Derek Sollenberger <djsollen@google.com>
7 files changed