The p4web binary installed by devel/p4web doesn't run on 10.x if the libstdc++.so.6 library is not available (on ad64, this is provided by compat9x-amd64 package on 10.x). The port should be able to depend upon compat9x-amd64 under 10.x releases.
The current Makefile contains a check for the problem you described: === start === # 10.x (and higher) needs compat libs .if ${OSVERSION} >= 1000054 LIB_DEPENDS+= libstdc++.so.6:${PORTSDIR}/misc/compat9x .endif === end === Therefore the PR could be closed. :)
Forgotten to close?
Reportedly fixed.