Created attachment 215119 [details]
patch to graphics/mesa-devel/Makefile
This allows a build of this port with poudriere on powerpc64 to at least get to:
Ignored: is only for amd64 i386, while you are running powerpc64 (reason: Limited scope: no old drivers and no software rendering.
rather than the uninformative information that it is skipped (libunwind).
I'm not going to add workarounds for what is already not supported. Open a bug against poudriere instead.