patch 8.1.1527: when moving popup window over the cmdline it is not redrawn

Problem:    When moving a popup window over the command line it is not
            redrawn.
Solution:   Redraw the command line. Move popup redrawing code to the popupwin
            file.
diff --git a/src/proto/popupwin.pro b/src/proto/popupwin.pro
index eeabafa..0b9dc42 100644
--- a/src/proto/popupwin.pro
+++ b/src/proto/popupwin.pro
@@ -24,4 +24,6 @@
 win_T *find_next_popup(int lowest);
 int popup_do_filter(int c);
 void popup_check_cursor_pos(void);
+void may_update_popup_mask(int type);
+void update_popups(void (*win_update)(win_T *wp));
 /* vim: set ft=c : */