mac: Make UseSystemDefaultHandler() clear handlers on failure

mac: Make UseSystemDefaultHandler() clear handlers on failure

If the task’s exception handler for EXC_CRASH, EXC_RESOURCE, and
EXC_GUARD exceptions cannot be set, clear the handler instead.

Nothing considered this function’s return value, and the only viable
fallback action on failure would have been to do what the function now
does, so its return type is changed to void.

R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/c95b30464ac1bfb03ccc197ec761f481e0fac391

[Mark Mentovai, 2015-10-05 19:24:09]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2015-10-05 20:54:04]

lgtm

[Mark Mentovai, 2015-10-05 21:12:08]

Committed patchset #1 (id:1) manually as
c95b30464ac1bfb03ccc197ec761f481e0fac391 (presubmit successful).