openmotif will not install Error: xorg-libXt must be installed with +flat_namespace

[fnajm (Farid Najm)]

I'm using the latest MacPorts on macOS X El Capitan Version 10.11.6 running on a Mac Pro (late 2013). The Mac is fully updated, using Xcode Version 7.3 (7D175). I installed many ports and all went fine, but openmotif will not install. I was actually trying to upgrade it and it came back with:

--->  Computing dependencies for openmotif
--->  Fetching archive for openmotif
Error: org.macports.archivefetch for port openmotif returned: xorg-libXt must be installed with +flat_namespace.
Please see the log file for port openmotif for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_x11_openmotif/openmotif/main.log
Error: Unable to upgrade port: 1
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
<Mac:3>

The main.log file that it refers to is attached.

[ryandesign (Ryan Carsten Schmidt)]

Do what the error message says to do: install xorg-libXt with +flat_namespace (by running sudo port upgrade --enforce-variants xorg-libXt +flat_namespace).