(backport from rev. 54154)

"extending and embedding" tutorial.
 (backport from rev. 54150)

sq_ass_slice instead of the sq_slice slot.
 (backport from rev. 54139)

 (backport from rev. 54114)

 (backport from rev. 54088)

 (backport from rev. 53935)

Don't use a fixed temporary name (gdbm).
Don't use our own temp name creation (dbm).

 (backport from rev. 53787)

 (backport from rev. 53785)

 (backport from rev. 53783)

when considering whether to rerun libffi configure.

Fixes #847665.

at position 0. (backport from rev. 53752)

 (backport from rev. 53697)

lib/python/config, on "linux" and "gnu" systems.