patch 8.1.1811: popup window color cannot be set to "Normal"

Problem:    Popup window color cannot be set to "Normal".
Solution:   Check for non-empty 'wincolor' instead of zero attribute.
            (closes #4772)
diff --git a/src/screen.c b/src/screen.c
index 04d0e2f..55437e1 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -995,7 +995,7 @@
     if (*wp->w_p_wcr != NUL)
 	wcr_attr = syn_name2attr(wp->w_p_wcr);
 #ifdef FEAT_TEXT_PROP
-    if (WIN_IS_POPUP(wp) && wcr_attr == 0)
+    else if (WIN_IS_POPUP(wp))
 	wcr_attr = HL_ATTR(HLF_PNI);
 #endif
     return wcr_attr;
@@ -9210,8 +9210,8 @@
     /*
      * If there is a next window or a status line, we first try to delete the
      * lines at the bottom to avoid messing what is after the window.
-     * If this fails and there are following windows, don't do anything to avoid
-     * messing up those windows, better just redraw.
+     * If this fails and there are following windows, don't do anything to
+     * avoid messing up those windows, better just redraw.
      */
     did_delete = FALSE;
     if (wp->w_next != NULL || wp->w_status_height)
@@ -9241,7 +9241,7 @@
     if (screen_ins_lines(0, W_WINROW(wp) + row, line_count, (int)Rows, 0, NULL)
 								      == FAIL)
     {
-	    /* deletion will have messed up other windows */
+	// deletion will have messed up other windows
 	if (did_delete)
 	{
 	    wp->w_redr_status = TRUE;