Fix abs(long long) test in 32bit MSVC: need to calculate max value in Python as Cython assumes result to be Py_ssize_t (due to sizeof()), which is < sizeof(long long).

Configure another Cython option in test runner from *inside* the shard runner to support non-forking setups (i.e. Windows).

Configure Cython options in test runner from *inside* the shard runner to support non-forking setups (i.e. Windows).

More pypy3 fixes

Fixes a segfault on pypy3 due to the coroutine type missing tp_iternext in 5.8.

Last change accidentally disallowed mismatching 'nogil' assignments even when compatible. Reallow them, and clean up the last change a little.

Allow assignment of C function pointers with compatible exception declarations (not only exact matches).

Allow mismatches of broader exception declarations in .pxd signatures as long the implemented signature is covered.

Pass pyx_library kwargs to py_library

Previously, using "is_f_contig" and "is_c_contig" together would leave one of them undeclared.
Closes #1872.