patch 8.1.2295: if buffer of popup is in another window cursorline sign shows

Problem:    If buffer of popup is in another window cursorline sign shows.
Solution:   Check the group of the sign.
diff --git a/src/drawline.c b/src/drawline.c
index 2802859..54163c7 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -671,7 +671,7 @@
 #endif
 
 #ifdef FEAT_SIGNS
-    sign_present = buf_get_signattrs(wp->w_buffer, lnum, &sattr);
+    sign_present = buf_get_signattrs(wp, lnum, &sattr);
 #endif
 
 #ifdef LINE_ATTR