faulthandler: _sigsegv() and _sigabrt() don't accept parameters
faulthandler: test_gil_released() now uses _sigsegv() instead of _read_null(),
because _read_null() cannot be used on AIX. On AIX, reading from NULL is
allowed: the first page of memory is a mapped read-only on AIX.
(Merge 3.4) faulthandler: test_gil_released() now uses _sigsegv() instead of
_read_null(), because _read_null() cannot be used on AIX. On AIX, reading from
NULL is allowed: the first page of memory is a mapped read-only on AIX.

_read_null() and _sigabrt() don't accept parameters.
Remove pointless "vile hack" that can cause the build step to fail when some extension modules can't be imported.

See issue #5309 for the build failures, issue #458343 for the original motivation.
remove merge goop from f86fde20e9ce