patch 8.2.1595: cannot easily see what Vim sends to the terminal

Problem:    Cannot easily see what Vim sends to the terminal.
Solution:   Write output to the channel log if it contains terminal control
            sequences.  Avoid warnings for tputs() argument.

src/optionstr.c

@@ -1434,6 +1434,9 @@ did_set_string_option(
 	}
 	if (varp == &T_BE && termcap_active)
 	{
+#ifdef FEAT_JOB_CHANNEL
+	    ch_log_output = TRUE;
+#endif
 	    if (*T_BE == NUL)
 		// When clearing t_BE we assume the user no longer wants
 		// bracketed paste, thus disable it by writing t_BD.