Reland "Use bitmap to maintain which signal is being handled"

This reverts commit 9d0fc0b43a5c35287181fa66749b3a1794c72386.

Reason for revert: Dynamic memory allocation in signal handling code was causing
issues. Fit bitmap within pthread's pointer.

Original CL: https://android-review.git.corp.google.com/c/platform/art/+/2411973

Bug: 160737021
Test: art/test/testrunner/testrunner.py --host -t 2045-uffd
with https://android-review.git.corp.google.com/c/platform/art/+/2411972

Change-Id: Iac7e78639f16af09392985930a2e8702daaf3947
(cherry picked from commit 1be648d6ceeeef3b29956f00535625e5e44a4cba)
Merged-In: Iac7e78639f16af09392985930a2e8702daaf3947