Open development for 2.21
HPPA: Transition to new non-addon NPTL.

Merge roland/nptl-hppa to master, update and test for hppa-linux-gnu.

This commit squashes and commits the work done by Roland McGrath on
roland/nptl-hppa to migrate hppa to the new non-addon NPTL. Some
additional tweaks were required for tcb-offsets.sym to work correctly
along with clone.S (unique to hppa).
HPPA: Add c++-types.data.

Added c++-types.data to baseline for HPPA. At this point `make check`
completes without error, and the full testing results are summarized.