autoupdate: AU_ALIAS shouldn't affect itself

Say I have an M4 macro file with an AU_ALIAS usage in it like this:

AU_ALIAS([BNV_HAVE_QT], [AX_HAVE_QT])

If I run autoupdate on this file, that will become:

AU_ALIAS([AX_HAVE_QT], [AX_HAVE_QT])

This seems pointless, as now the AU_ALIAS won't do what it was originally
meant to do anymore. Perhaps autoupdate could be updated to stop making
this change.

Thanks,
Eric Gallager