patch 8.1.2245: third character of 'listchars' tab shows in wrong place

Problem:    Third character of 'listchars' tab shows in wrong place when
            'breakindent' is set.
Solution:   Set c_final to NUL. (Naruhiko Nishino, closes #5165)
diff --git a/src/drawline.c b/src/drawline.c
index dcfe92c..ea9e4a9 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -1173,6 +1173,7 @@
 # endif
 		    p_extra = NULL;
 		    c_extra = ' ';
+		    c_final = NUL;
 		    n_extra = get_breakindent_win(wp,
 				       ml_get_buf(wp->w_buffer, lnum, FALSE));
 		    // Correct end of highlighted area for 'breakindent',
@@ -1647,9 +1648,8 @@
 #ifdef FEAT_LINEBREAK
 	    int c0;
 #endif
+	    VIM_CLEAR(p_extra_free);
 
-	    if (p_extra_free != NULL)
-		VIM_CLEAR(p_extra_free);
 	    // Get a character from the line itself.
 	    c = *ptr;
 #ifdef FEAT_LINEBREAK