Issue #25262. Added support for BINBYTES8 opcode in Python implementation of

unpickler.  Highest 32 bits of 64-bit size for BINUNICODE8 and BINBYTES8
opcodes no longer silently ignored on 32-bit platforms in C implementation.

diff --cc Lib/pickle.py
Simple merge

diff --cc Lib/test/pickletester.py
Simple merge

diff --cc Misc/NEWS
Simple merge

diff --cc Modules/_pickle.c
Simple merge