Using a different version of doxygen produces a lot of missing tag output

If the version of doxygen that is used is not the same version that wxWidgets needs a lot of missing tag messages is displayed. I think it would be best if the line in the build.py file that has this "os.environ['WX_SKIP_DOXYGEN_VERSION_CHECK'] = '1'" be set to zero or commented out. When I used version doxygen v1.8.8 with wxWidgets 3.1.5 almost all of the missing tag messages went away.
