* net/tramp-cache.el (tramp-get-file-property)
(tramp-set-file-property): Check, that `tramp-cache-get-count-*'
and `tramp-cache-set-count-*' are bound.  Otherwise, there might
be compiler warnings.

* net/tramp-sh.el (tramp-get-remote-uid, tramp-get-remote-gid):
Return -1 respective "UNKNOWN", if uid or gid cannot be determined.