Some Tramp minor fixes, found during test campaign.
* net/tramp-adb.el (tramp-adb-file-name-handler-alist)
[make-symbolic-link]: Use `tramp-handle-make-symbolic-link'.
* net/tramp-gvfs.el (tramp-gvfs-file-name-handler-alist)
[make-symbolic-link]: Use `tramp-handle-make-symbolic-link'.
(tramp-gvfs-maybe-open-connection): Set always connection
properties, even if target is mounted already.
* net/tramp-sh.el (tramp-color-escape-sequence-regexp):
Set tramp-autoload cookie.
(tramp-get-remote-touch): New defun.
(tramp-sh-handle-set-file-times): Use it.
(tramp-sh-handle-directory-files-and-attributes):
Use `tramp-handle-directory-files-and-attributes' if neither stat
nor perl are available on the remote host.
* net/tramp-smb.el (tramp-smb-handle-insert-directory): Mark trailing
"/". Write long listing only when "l" belongs to the switches.
* net/tramp.el (tramp-handle-make-symbolic-link): New defun.
(tramp-check-cached-permissions): Call `file-attributes' if the
cache is empty.