Move less common ref-counting cases for memory views out of the fast-path and only look up the atomic acquisition count value once per INC/DEC operation.

When it's merged into the main module, wrap it in a CompilerDirectivesNode.

Also mark the case of an uninitialised memory view slice as "unlikely()" when refcounting it since it's most probably not a performance critical case.

Mark the last deletion of a memory view slice as "unlikely()" to ask the C compiler to optimise for the repeated re-use case (usually in loops).

Mark the first creation of a memory view slice as "unlikely()" to ask the C compiler to optimise for the repeated re-use case (usually in loops).

Fix up the NumPy warnings hack by using the actual "import_array()" function declaration instead of a wrong one.

Also mark the case of an uninitialised memory view slice as "unlikely()" when refcounting it since it's most probably not a performance critical case.

Mark the last deletion of a memory view slice as "unlikely()" to ask the C compiler to optimise for the repeated re-use case (usually in loops).

Mark the first creation of a memory view slice as "unlikely()" to ask the C compiler to optimise for the repeated re-use case (usually in loops).

Closes https://github.com/cython/cython/issues/3594

Closes https://github.com/cython/cython/issues/1462

Move the work directory of the examples tests into an 'examples/' subdirectory to get it out of the way of the other test types.

Move the work directory of the examples tests into an 'examples/' subdirectory to get it out of the way of the other test types.