* cygheap.h (cwdstuff::override_win32_cwd): Declare.

	* cygheap.h (cwdstuff::override_win32_cwd): Declare.
	* ntdll.h (struct _PEB): Add members accessed by the fast cwd method
	starting with Vista.
	(struct _KUSER_SHARED_DATA): Define with only the DismountCount.
	(RtlAllocateHeap): Declare.
	(RtlEnterCriticalSection): Declare.
	(RtlFreeHeap): Declare.
	(RtlLeaveCriticalSection): Declare.
	* path.cc (get_user_proc_parms): Remove.
	(struct _FAST_CWD): New structure.
	(fast_cwd_ptr): Define.
	(SharedUserData): Define.
	(peek32): Define.
	(find_fast_cwd_pointers): New function to find the global pointer
	to the current FAST_CWD structure.
	(copy_cwd_str): New helper function.
	(cwdstuff::override_win32_cwd): New method to set the Win32 CWD.
	(cwdstuff::init): Just call override_win32_cwd from here when
	started from native Win32 parent.
	(cwdstuff::set): Access Win32 CWD via PEB reference instead of using
	get_user_proc_parms function.  Memorize old DismountCount before
	opening directory handle.  Call override_win32_cwd to set up Win32 CWD.
	Be more verbose in comments.
	* wincap.h (wincaps::has_fast_cwd): New element.
	* wincap.cc: Implement has_fast_cwd element throughout.