--->  Building libunwind-headers
Error: org.macports.build for port libunwind-headers returned: command execution failed
Please see the log file for port libunwind-headers for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_devel_libunwind-headers/libunwind-headers/main.log
Error: Problem while installing libunwind-headers
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets