[lmi] wx_test: output strings truncated to one character

[Greg Chicares]

Building and running lmi (HEAD) in msw-7, we observe that this
code in 'wx_test_about_version.cpp':
  // Extract the last word of the dialog title.
  wxString const last_word = d->GetTitle().AfterLast(' ');
  wxPrintf("About dialog version string is \"%s\".\n", last_word);
  LMI_ASSERT_EQUAL(last_word, LMI_VERSION);
prints:
  About dialog version string is "2".
but LMI_VERSION is:
  #define LMI_VERSION "20160114T1914Z"
and the assertion above succeeds, so it seems that the wxString
is correct but something is wrong with wxPrintf().