CPython bpo-37221 reverts that backwards incompatible
change to the PyCode_New API, replacing it with a new
PyCode_NewWithPosOnlyArgs function.

PyGILState_STATE was added in commit 3fd6fdce (Gilnanny + pystate.pxd)
with struct type on-purpose different from what CPython actually uses
with the idea so that PyGILState_STATE cannot be coerced into int.

However as it is, it prevents PyGILState_STATE usage:

	cdef PyGILState_STATE gstate = PyGILState_Ensure()

gives

	Variable type 'PyGILState_STATE' is incomplete

Fix it by making PyGILState_STATE a defined structure.

Closes GH-3007.

The regex to match the gdb version is not intended to be interpreted as a regular string, it is designed to be used as-is as a regex.  This lets python know that minor detail.

And make it more flexible in terms of API change.

And make it more flexible in terms of API change.

Current checks breaks when setting 0.10.0 as a Pythran version :-/

Add compatability with Bazel 0.26

Make co_argcount for positional-only arguments behave correctly, now that CPython 3.8 (beta 1) includes the pos-only count in it rather than adding it.

Avoid checking Py_TPFLAGS_HAVE_FINALIZE in Py3.8 and later since CPython now relies on the feature being there.

Fixes GH-2941.

Closes GH-2976.

When passing keyword arguments from unpacked dict literals, prevent duplicate dict keys from raising an error and instead overwrite the previous one.
Closes GH-2963.