* cygheap.h (enum fcwd_version_t): Move here from path.cc.

	* cygheap.h (enum fcwd_version_t): Move here from path.cc.
	(class fcwd_access_t): Ditto.  Only declare methods.
	(class cwdstuff): Move fast_cwd_ptr and fast_cwd_version from shared
	DLL section here.
	* path.cc: Keep fcwd_access_t method definitions.
	(fcwd_access_t::fast_cwd_version): New method.
	(find_fast_cwd_pointer): Change comment.  Mention test on W8CP.
	(cwdstuff::init): Initialize fast_cwd_ptr and fast_cwd_version.