Issue #17173: Remove uses of locale-dependent C functions (isalpha() etc.) in the...

I've left a couple of them in: zlib (third-party lib), getaddrinfo.c
(doesn't include Python.h, and probably obsolete), _sre.c (legitimate
use for the re.LOCALE flag), mpdecimal (needs to build without Python.h).

diff --cc Misc/NEWS
Simple merge

diff --cc Modules/_struct.c
Simple merge

diff --cc Objects/longobject.c
Simple merge

diff --cc Python/ast.c
Simple merge

diff --cc Python/formatter_unicode.c
Simple merge