inc/sys/stat.h (struct stat): Change the types of st_uid and st_gid to unsigned.

inc/sys/stat.h (struct stat): Change the types of st_uid and st_gid to unsigned.

inc/pwd.h (struct passwd): Change the types of pw_uid and pw_gid to unsigned.
	  (getpwuid): Argument is now unsigned.
	  uid_t is now unsigned.

ntlib.c (setuid): Argument is now unsigned.
	(getuid): Return value is now unsigned.
	(getpwuid): Argument is now unsigned.
	(fchown): UID and GID arguments are now unsigned.

ntlib.h (fchown): UID and GID arguments are now unsigned.
	(getuid): Return value is now unsigned.
	(setuid): Argument is now unsigned.
	(getpwuid): Remove prototype (it's declared in nt/inc/pwd.h).

w32.c   (getpwuid): Change argument type to unsigned.
	(struct w32_id): Change type of `rid' member to unsigned.
	(w32_cached_id, w32_add_to_cache, get_name_and_id): Change type of
	argument ID to unsigned.  All callers changed.
	(getuid, geteuid, getgid, getegid): Change return type to unsigned.