Issue #21201: Improves readability of multiprocessing error message from server to client for certain exceptions

Patch by Claude Paroz.

Initial patch contributed by Denver Coneybeare.

between runs given the same Grammar.txt input regardless of the hash
randomization setting.

required for PGO linking - to be a configure time error rather than
make time when --with-optimizations is enabled.  Also improve our
ability to find the llvm-profdata tool on MacOS and some Linuxes.

Original patch by Martin Panter, new policy fixes by me.

modules.

Initial patch by Alex LordThorsen.

Issue #27960: Revert state to 675e20c38fdac6, backing out all changes by developed for Issue #12885.

Initial patch contributed by Jaysinh shukla.

It is unused. It also forces a 16-byte alignment, which creates problems because
Python's allocator only uses 8-byte alignment.

Apparently the test succeeds on XP.