patch 8.1.1528: popup_any_visible() is unused

Problem:    Popup_any_visible() is unused.
Solution:   Remove it.
diff --git a/src/popupwin.c b/src/popupwin.c
index 85bbac8..5265b4b 100644
--- a/src/popupwin.c
+++ b/src/popupwin.c
@@ -934,23 +934,6 @@
 }
 
 /*
- * Return TRUE if there any popups that are not hidden.
- */
-    int
-popup_any_visible(void)
-{
-    win_T *wp;
-
-    for (wp = first_popupwin; wp != NULL; wp = wp->w_next)
-	if ((wp->w_popup_flags & POPF_HIDDEN) == 0)
-	    return TRUE;
-    for (wp = curtab->tp_first_popupwin; wp != NULL; wp = wp->w_next)
-	if ((wp->w_popup_flags & POPF_HIDDEN) == 0)
-	    return TRUE;
-    return FALSE;
-}
-
-/*
  * Invoke the close callback for window "wp" with value "result".
  * Careful: The callback may make "wp" invalid!
  */
diff --git a/src/proto/popupwin.pro b/src/proto/popupwin.pro
index 0b9dc42..cde0cae 100644
--- a/src/proto/popupwin.pro
+++ b/src/proto/popupwin.pro
@@ -9,7 +9,6 @@
 void f_popup_create(typval_T *argvars, typval_T *rettv);
 void f_popup_atcursor(typval_T *argvars, typval_T *rettv);
 void f_popup_notification(typval_T *argvars, typval_T *rettv);
-int popup_any_visible(void);
 void f_popup_close(typval_T *argvars, typval_T *rettv);
 void f_popup_hide(typval_T *argvars, typval_T *rettv);
 void f_popup_show(typval_T *argvars, typval_T *rettv);
diff --git a/src/version.c b/src/version.c
index 1356fda..aa3986d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1528,
+/**/
     1527,
 /**/
     1526,