What irks me the most is that `{.nimcall.}` is not the same as `{.cdecl.}`,
even though they're functionally identical on every platform except for win32.
Making {.nimcall.} == {.cdecl.} would remove a substantial chunk of ffi
friction, and wouldn't change anything, practically speaking.
So that's the 'breaking' change I'd wish for
