patch 8.0.1336: cannot use imactivatefunc() unless compiled with +xim

Problem:    Cannot use imactivatefunc() unless compiled with +xim.
Solution:   Allow using imactivatefunc() when not compiled with +xim.
            (Yasuhiro Matsumoto, closes #2349)

src/testdir/test_iminsert.vim

@@ -0,0 +1,29 @@
+if !has('multi_byte')
+  finish
+endif
+
+source view_util.vim
+
+let s:imactivatefunc_called = 0
+let s:imstatusfunc_called = 0
+
+func IM_activatefunc(active)
+  let s:imactivatefunc_called = 1
+endfunc
+
+func IM_statusfunc()
+  let s:imstatusfunc_called = 1
+  return 0
+endfunc
+
+func Test_iminsert2()
+  set imactivatefunc=IM_activatefunc
+  set imstatusfunc=IM_statusfunc
+  set iminsert=2
+  normal! i
+  set iminsert=0
+  set imactivatefunc=
+  set imstatusfunc=
+  call assert_equal(1, s:imactivatefunc_called)
+  call assert_equal(1, s:imstatusfunc_called)
+endfunc