re PR libffi/40807 (libffi.call/return_sc.c)

re PR libffi/40807 (libffi.call/return_sc.c)

	PR libffi/40807
	* src/x86/ffi.c (ffi_prep_cif_machdep): Also use sign/zero-extending
	return types for X86_WIN32.
	* src/x86/win32.S (_ffi_call_SYSV): Handle omitted return types.
	(_ffi_call_STDCALL, _ffi_closure_SYSV, _ffi_closure_raw_SYSV,
	_ffi_closure_STDCALL): Likewise.

	* src/closures.c (is_selinux_enabled): Define to const 0 for Cygwin.
	(dlmmap, dlmunmap): Also use these functions on Cygwin.

From-SVN: r150042