* include/winbase.h [_WIN32_WINNT >= 0x0501] (ACTCTX_FLAG_*):

	* include/winbase.h [_WIN32_WINNT >= 0x0501] (ACTCTX_FLAG_*):
	Add constants.

	* include/winbase.h [_WIN32_WINNT >= 0x0501] (ACTCTX[AW]): Add
	structures.

	* include/winbase.h [_WIN32_WINNT >= 0x0501] (ActivateActCtx): Add
	function. MSDN says the first argument is HACTCTX but I'm not sure
	where such a specialized handle is defined, so use HANDLE instead.

	* include/winbase.h [_WIN32_WINNT >= 0x0501] (AttachConsole,
	CheckNameLegalDOS8Dot3[AW]): Add functions.

	* lib/user32.def (ActivateActCtx, AttachConsole,
	CheckNameLegalDOS8Dot3[AW]): Add functions.

	* lib/user32.def (AddLocalAlternateComputerName[AW]): Add functions.
	Unfortunately I don't know which header to put the declarations in.