patch 9.1.0084: Visual hl wrong when it ends before multibyte 'showbreak'

Problem:  Visual hl wrong when it ends before multibyte 'showbreak'.
          (lacygoil)
Solution: Use vcol_sbr instead of adding n_extra.
          (zeertzjq)

fixes: #11272
closes: #13996

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/drawline.c b/src/drawline.c
index f6c01d5..0f3400f 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -589,7 +589,7 @@
 	// Correct end of highlighted area for 'showbreak',
 	// required when 'linebreak' is also set.
 	if (wlv->tocol == wlv->vcol)
-	    wlv->tocol += wlv->n_extra;
+	    wlv->tocol = wlv->vcol_sbr;
 	// combine 'showbreak' with 'wincolor'
 	wlv->char_attr = hl_combine_attr(wlv->win_attr, HL_ATTR(HLF_AT));
 #  ifdef FEAT_SYN_HL