patch 8.0.1341: 'imactivatefunc' test fails on MS-Windows

Problem:    'imactivatefunc' test fails on MS-Windows.
Solution:   Skip the text.
diff --git a/src/testdir/test_iminsert.vim b/src/testdir/test_iminsert.vim
index 603135a..0676c03 100644
--- a/src/testdir/test_iminsert.vim
+++ b/src/testdir/test_iminsert.vim
@@ -17,6 +17,9 @@
 endfunc
 
 func Test_iminsert2()
+  if has('gui_win32')
+    return
+  endif
   set imactivatefunc=IM_activatefunc
   set imstatusfunc=IM_statusfunc
   set iminsert=2