OpenMPI is broken for PPC: configure: error: Big endian PPC is no longer supported

[barracuda156]

Ref: ​https://build.macports.org/builders/ports-10.5_ppc_legacy-builder/builds/93564/steps/install-port/logs/stdio

============================================================================
== Configuring Open MPI
============================================================================

*** Startup tests
checking build system type... powerpc-apple-darwin9.8.0
checking host system type... powerpc-apple-darwin9.8.0
checking target system type... powerpc-apple-darwin9.8.0
configure: error: Big endian PPC is no longer supported.
Command failed:  cd "/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_science_openmpi/openmpi-default/work/build" && /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_science_openmpi/openmpi-default/work/openmpi-3.0.0/configure --prefix=/opt/local --enable-mpi-cxx FFLAGS='' F77='' --bindir=/opt/local/libexec/openmpi-mp --libdir=/opt/local/lib/openmpi-mp --sysconfdir=/opt/local/etc/openmpi-mp --includedir=/opt/local/include/openmpi-mp --datadir=/opt/local/share/openmpi-mp --docdir=/opt/local/share/docdelete --mandir=/opt/local/share/mandelete --with-hwloc=/opt/local --enable-mpi-fortran 
Exit code: 1