I would like to tweak glibc so that it only builds one POWER 620/970
libc for ppc64, and not multiple libcs with POWER6/POWER7/POWER8
This does not affect ppc64le in any way.
The reason for this change is that the ppc64 builders are awfully slow
as of late, and the multiple builds (four times currently) currently
make ppc64 the slowest architecture to build by quite a margin.