patch 8.1.1088: height of quickfix window not retained with vertical split

Problem:    Height of quickfix window not retained with vertical split.
Solution:   Use frame_fixed_height() and frame_fixed_width(). (Hongbo Liu,
            closes #4013, closes #2998)
diff --git a/src/window.c b/src/window.c
index 6c9c705..b905fbf 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2677,10 +2677,10 @@
 	    {
 		if (frp != NULL)
 		{
-		    if (frp->fr_win != NULL && !frp->fr_win->w_p_wfh)
+		    if (!frame_fixed_height(frp))
 		    {
 			frp2 = frp;
-			wp = frp->fr_win;
+			wp = frame2win(frp2);
 			break;
 		    }
 		    frp = frp->fr_prev;
@@ -2714,10 +2714,10 @@
 	    {
 		if (frp != NULL)
 		{
-		    if (frp->fr_win != NULL && !frp->fr_win->w_p_wfw)
+		    if (!frame_fixed_width(frp))
 		    {
 			frp2 = frp;
-			wp = frp->fr_win;
+			wp = frame2win(frp2);
 			break;
 		    }
 		    frp = frp->fr_prev;