Remove obsolete sanitise_term_data().

The previous commit removed its last use, so now we can garbage-
collect it, including its long-standing FIXME comment which is now
fulfilled by the new StripCtrlChars system.

misc.h

@@ -137,8 +137,6 @@ static inline void bufchain_set_callback(bufchain *ch, IdempotentCallback *ic)
     bufchain_set_callback_inner(ch, ic, queue_idempotent_callback);
 }
 
-void sanitise_term_data(bufchain *out, const void *vdata, size_t len);
-
 bool validate_manual_hostkey(char *key);
 
 struct tm ltime(void);

utils.c

@@ -756,32 +756,6 @@ size_t bufchain_fetch_consume_up_to(bufchain *ch, void *data, size_t len)
     return len;
 }
 
-/* ----------------------------------------------------------------------
- * Sanitise terminal output that we have reason not to trust, e.g.
- * because it appears in the login banner or password prompt from a
- * server, which we'd rather not permit to use arbitrary escape
- * sequences.
- */
-
-void sanitise_term_data(bufchain *out, const void *vdata, size_t len)
-{
-    const char *data = (const char *)vdata;
-
-    /*
-     * FIXME: this method of sanitisation is ASCII-centric. It would
-     * be nice to permit SSH banners and the like to contain printable
-     * Unicode, but that would need a lot more complicated code here
-     * (not to mention knowing what character set it should interpret
-     * the data as).
-     */
-    for (size_t i = 0; i < len; i++) {
-        if (data[i] == '\n')
-            bufchain_add(out, "\r\n", 2);
-        else if (data[i] >= ' ' && data[i] < 0x7F)
-            bufchain_add(out, data + i, 1);
-    }
-}
-
 /* ----------------------------------------------------------------------
  * Debugging routines.
  */