In the future, please use WikiFormatting. Trac requires complete email addresses and Cc'ing "openmaintainer" is not useful since it does not go to anyone.
There is nothing to fix here. The libstdcxx and libstdcxx-devel ports conflict, so do what the output says and just use libstdcxx-devel.
Image error: /opt/local/lib/.libstdcxx is being used by the active libstdcxx port.
Please deactivate this port first, or use 'port -f activate libstdcxx-devel' to force the activation.
The wording isn't so good though. So do this:
sudo port -f deactivate libstdcxx
sudo port activate libstdcxx-devel
