patch 8.1.1862: Coverity warns for not using return value

Problem:    Coverity warns for not using return value.
Solution:   Add "(void)" to avoid the warning.
diff --git a/src/normal.c b/src/normal.c
index 2067542..7951bd5 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -8065,7 +8065,7 @@
 	    {
 		if (cap->count1 > 1)
 		    // if it fails, let the cursor still move to the last char
-		    cursor_down(cap->count1 - 1, FALSE);
+		    (void)cursor_down(cap->count1 - 1, FALSE);
 
 		i = curwin->w_leftcol + curwin->w_width - col_off - 1;
 		coladvance((colnr_T)i);