Adds a flag (--disable-in-process-stack-traces) to not install
signal handlers so that e.g. ASan signal handlers will work.

This flag mirrors chromium's one.

R=jochen@chromium.org
BUG=chromium:716235

Review-Url: https://codereview.chromium.org/2854173002
Cr-Commit-Position: refs/heads/master@{#45142}