patch 9.1.1021: string might be used without a trailing NUL

Problem:  string might be used without a trailing NUL (after v9.1.0997)
Solution: Make sure that the buffer is NUL terminated

closes: #16457

Signed-off-by: John Marriott <[email protected]>
Signed-off-by: Christian Brabandt <[email protected]>

Author: basilisk0315

src/drawscreen.c

@@ -479,7 +479,10 @@ win_redr_status(win_T *wp, int ignore_pum UNUSED)
 		    || bufIsChanged(wp->w_buffer)
 		    || wp->w_buffer->b_p_ro)
 		&& plen < MAXPATHL - 1)
-	    *(p + plen++) = ' ';
+	{
+	    *(p + plen++) = ' ';	// replace NUL with space
+	    *(p + plen) = NUL;		// NUL terminate the string
+	}
 	if (bt_help(wp->w_buffer))
 	    plen += vim_snprintf((char *)p + plen, MAXPATHL - plen, "%s", _("[Help]"));
 #ifdef FEAT_QUICKFIX

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1021,
 /**/
     1020,
 /**/