Print what crashed DM on Android too.

This doesn't print a backtrace, but it's better than nothing.
By preserving the original signal handler and calling into that, we keep the Android system stack trace, visible in logcat, the "dump log" step on bots. 

Tested locally on Mac and Android by making an arbitrary GM segfault.

BUG=skia:5876

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3860

Change-Id: Ia7a962ca50e09d370423a6106033e34c47d7643d
Reviewed-on: https://skia-review.googlesource.com/3860
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed