patch 8.1.1754: build failure

Problem:    Build failure.
Solution:   Add missing change to window struct.
diff --git a/src/structs.h b/src/structs.h
index ac23362..5841176 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -3017,7 +3017,10 @@
     int		w_popup_drag;	    // allow moving the popup with the mouse
     popclose_T	w_popup_close;	    // allow closing the popup with the mouse
 
-    list_T	*w_popup_mask;	    // list of lists for "mask"
+    list_T	*w_popup_mask;	     // list of lists for "mask"
+    char_u	*w_popup_mask_cells; // cached mask cells
+    int		w_popup_mask_height; // height of w_popup_mask_cells
+    int		w_popup_mask_width;  // width of w_popup_mask_cells
 # if defined(FEAT_TIMERS)
     timer_T	*w_popup_timer;	    // timer for closing popup window
 # endif
diff --git a/src/version.c b/src/version.c
index 64f6a9e..1ae8910 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1754,
+/**/
     1753,
 /**/
     1752,