patch 9.0.1084: code handling low level MS-Windows events cannot be tested

Problem:    Code handling low level MS-Windows events cannot be tested.
Solution:   Add test_mswin_event() and tests using it. (Christopher Plewright,
            closes #11622)
diff --git a/src/proto/gui_w32.pro b/src/proto/gui_w32.pro
index cab3343..c5c6585 100644
--- a/src/proto/gui_w32.pro
+++ b/src/proto/gui_w32.pro
@@ -96,5 +96,5 @@
 BalloonEval *gui_mch_create_beval_area(void *target, char_u *mesg, void (*mesgCB)(BalloonEval *, int), void *clientData);
 void gui_mch_destroy_beval_area(BalloonEval *beval);
 void netbeans_draw_multisign_indicator(int row);
-int test_gui_w32_sendevent(dict_T *args);
+int test_gui_w32_sendevent(char_u *event, dict_T *args);
 /* vim: set ft=c : */