libunwind-headers issue

[Werner LEMBERG]

On Mac Lion, installing a fresh MacPorts from scratch, then calling

  port -N mpkg lilypond-devel +mactex +perl5_28 +python37

always causes a (harmless) abort.  The reason is that
`libunwind-headers' gets installed as part of the dependencies rather
early, but one of the very last steps is installation of `libgcc9',
which doesn't work with activated `libunwind-headers'.

Is it possible to somehow tell `port' in the above command that
`libunwind-headers' has to be deactivated before building `libgcc9'?


    Werner