patch 8.0.1136: W_WIDTH() is always the same

Problem:    W_WIDTH() is always the same.
Solution:   Expand the macro.
diff --git a/src/gui_beval.c b/src/gui_beval.c
index 2dbce7e..1c01ecc 100644
--- a/src/gui_beval.c
+++ b/src/gui_beval.c
@@ -338,7 +338,7 @@
     row = Y_2_ROW(beval->y);
     col = X_2_COL(beval->x);
     wp = mouse_find_win(&row, &col);
-    if (wp != NULL && row < wp->w_height && col < W_WIDTH(wp))
+    if (wp != NULL && row < wp->w_height && col < wp->w_width)
     {
 	/* Found a window and the cursor is in the text.  Now find the line
 	 * number. */