patch 8.2.3735: cannot use a lambda for 'imactivatefunc'

Problem:    Cannot use a lambda for 'imactivatefunc'.
Solution:   Add lambda support for 'imactivatefunc' and 'imstatusfunc'.
            (Yegappan Lakshmanan, closes #9275)
diff --git a/src/proto/gui_xim.pro b/src/proto/gui_xim.pro
index 01fb56c..60f30d7 100644
--- a/src/proto/gui_xim.pro
+++ b/src/proto/gui_xim.pro
@@ -1,4 +1,7 @@
 /* gui_xim.c */
+int set_imactivatefunc_option(void);
+int set_imstatusfunc_option(void);
+void free_xim_stuff(void);
 void im_set_active(int active);
 void xim_set_focus(int focus);
 void im_set_position(int row, int col);