Fix error in Tramp rsync method

* lisp/net/tramp-sh.el (tramp-methods) <rsync>: Add "-c" argument.
Otherwise, `tramp-test10-write-region' could fail.

lisp/net/tramp-sh.el

@@ -200,7 +200,7 @@ The string is used in `tramp-methods'.")
     (tramp-remote-shell-login   ("-l"))
     (tramp-remote-shell-args    ("-c"))
     (tramp-copy-program         "rsync")
-    (tramp-copy-args            (("-t" "%k") ("-p") ("-r") ("-s")))
+    (tramp-copy-args            (("-t" "%k") ("-p") ("-r") ("-s") ("-c")))
     (tramp-copy-env             (("RSYNC_RSH") ("ssh" "%c")))
     (tramp-copy-keep-date       t)
     (tramp-copy-keep-tmpfile    t)