Since https://crrev.com/c/1335572, our sanitizers allow to set custom
segfault handlers. Thus remove special code that was added to handle
sanitizers that prevent installation of segfault handlers. Instead,
CHECK that the signal handler was installed correctly.

R=ahaas@chromium.org, mseaborn@chromium.org, mark@chromium.org

Bug: chromium:830894
Change-Id: I3bd66e33efdceb3e8469f3f4a09fbde90cb3d7ec
Reviewed-on: https://chromium-review.googlesource.com/c/1392199Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58513}