Rosetta2 and supported_archs

[Craig Treleaven]

A user with a new Apple Silicon-based Mac had a go at building mythtv.28.  It failed thusly:

--->  Computing dependencies for mythtv.28
Error: Cannot install mythtv-core.28 for the arch 'x86_64' because
Error: its dependency logrotate does not build for the required arch by
default

https://trac.macports.org/ticket/62027

Given Rosetta2 on these systems, isn’t this a bogus error?  On M1 Macs, we might warn that a dependency is being built for an arch different from that of the main target but why should it be a fatal error?

What was done during the PPC to Intel transition? Did we try to force all deps of a port to build with the same arch?

Craig