Simplify handling of MTREEFILE relative to DESTDIR
Simplify handling of MTREEFILE relative to DESTDIR

Make the message about a missing MTREEFILE combined with -U
more informative

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase