Support symbolization on PA-RISC

Support symbolization on PA-RISC

Forwarded: yes
Applied-Upstream: https://github.com/abseil/abseil-cpp/commit/7f850b3167fb38e6b4a9ce1824e6fabd733b5d62

Null out supervisor bits in PA-RISC addresses before symbolizing, and
handle function descriptor tables correctly.

Change symbolize_test.cc to use 32-bit aligned addresses, allowing that
test to pass on PA-RISC.

The author works at Google. Upstream applied this patch as Piper
revision 428590564 and exported it to GitHub; the Applied-Upstream URL
above points to the exported commit.

Gbp-Pq: Name hppa-symbolize.diff