patch 9.0.0032: in the quickfix window 'cursorline' overrules QuickFixLine

Problem:    In the quickfix window 'cursorline' overrules QuickFixLine
            highlighting.
Solution:   Combine the attributes.  Add a test. (closes #10654)
diff --git a/src/drawline.c b/src/drawline.c
index 51a5fbf..d87d800 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -970,7 +970,11 @@
 		}
 		else
 # endif
+# if defined(FEAT_QUICKFIX)
+		    line_attr = hl_combine_attr(line_attr, cul_attr);
+# else
 		    line_attr = cul_attr;
+# endif
 	    }
 	    else
 	    {