In Tramp. check ssh Control* options only when needed
Fixes: debbugs:20015
* net/tramp-adb.el:
* net/tramp-gvfs.el:
* net/tramp-sh.el:
* net/tramp-smb.el: Set tramp-autoload cookie for all defcustoms.
* net/tramp-sh.el (tramp-use-ssh-controlmaster-options):
New defcustom, moved from tramp.el.
(tramp-ssh-controlmaster-options): New defvar, moved from tramp.el
but with a nil initial value.
(tramp-ssh-controlmaster-options): New defun.
(tramp-do-copy-or-rename-file-out-of-band)
(tramp-maybe-open-connection): Use it.
* net/tramp.el (tramp-ssh-controlmaster-options)
(tramp-use-ssh-controlmaster-options): Move them to tramp-sh.el.
(tramp-default-method): Do not check for
`tramp-ssh-controlmaster-options'.