bpo-33005: Fix _PyGILState_Reinit() (GH-6001)


Fix a crash on fork when using a custom memory allocator (ex: using
PYTHONMALLOC env var).

_PyGILState_Reinit() and _PyInterpreterState_Enable() now use the
default RAW memory allocator to allocate a new interpreters mutex on
fork.
(cherry picked from commit 5d92647102fac9e116b98ab8bbc632eeed501c34)

Co-authored-by: Victor Stinner <victor.stinner@gmail.com>
2 files changed