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/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 886bb08..fdca9f4 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -210,6 +210,7 @@
 	test_modeless \
 	test_modeline \
 	test_move \
+	test_mswin_event \
 	test_mzscheme \
 	test_nested_function \
 	test_netbeans \
@@ -454,6 +455,7 @@
 	test_mksession.res \
 	test_modeless.res \
 	test_modeline.res \
+	test_mswin_event.res \
 	test_mzscheme.res \
 	test_nested_function.res \
 	test_netbeans.res \