patch 8.0.0244: making t_BE empty only has an effect before startup

Problem:    When the user sets t_BE empty after startup to disable bracketed
            paste, this has no direct effect.
Solution:   When t_BE is made empty write t_BD.  When t_BE is made non-empty
            write the new value.

src/option.c

@@ -6619,6 +6619,15 @@ did_set_string_option(
 	    mch_set_normal_colors();
 #endif
 	}
+	if (varp == &T_BE && termcap_active)
+	{
+	    if (*T_BE == NUL)
+		/* When clearing t_BE we assume the user no longer wants
+		 * bracketed paste, thus disable it by writing t_BD. */
+		out_str(T_BD);
+	    else
+		out_str(T_BE);
+	}
     }
 
 #ifdef FEAT_LINEBREAK

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    244,
 /**/
     243,
 /**/