* path.h (path_conv): Make path_flags private. Rename known_suffix to

	* path.h (path_conv): Make path_flags private.  Rename known_suffix to
	suffix and make private.  Rename normalized_path to posix_path and
	make privtae.  Accommodate name changes throughout in path_conv
	methods.
	(path_conv::known_suffix): New method.  Use throughout instead of
	accessing suffix directly.
	(path_conv::get_win32): Constify.
	(path_conv::get_posix): New method to read posix_path.  Use throughout
	instead of accessing normalized_path directly.
	(path_conv::set_posix): Rename from set_normalized_path.  Accommodate
	name change throughout.
	* spawn.cc (find_exec): Return POSIX path, not Win32 path.