"synchapi.h" is not supposed to be included directly, and "windows.h" can break ... other stuff.
Let's see what we can do.

Looks like the usual macro on Windows is "_WIN32" and not "WIN32". Let's support both, to be on the safe side.

Move a memoryview test out of the "run" test directory since memoryview tests tend to be slow and have their own test directory.

- hash() hashing lead to unpredictable random prefixes for long names across multiple runs
- use a single regex run instead of repeated calls to replace()

Fixes https://github.com/cython/cython/issues/3843

Run both in the same job since the machines are quite fast with parallel processes, but setting one up is slow.

See, for example, https://isocpp.org/blog/2012/11/universal-references-in-c11-scott-meyers

Closes #3814

Show a more detailed error for unspecializable fused return types.

Set language level in Cython's speed-up .pxd files since it no longer depends on the .py files that they correspond to.

Closes https://github.com/cython/cython/issues/2552

Keep AnnotationNode instead of the bare annotation expression in "entry.annotation" to get access to the string representation.

Do not include "u" string prefix in annotations since tools that process them probably expect Py3 string semantics anyway.

Prevent overflowing hash values for "Machines.Node" due to arbitrarily large unsigned pointer values.
Closes https://github.com/cython/cython/issues/3840

Specifically this allows public packed structs but may also allow other public declarations that require small amounts of utility code.