It is marked BROKEN on amd64 because FreeBSD/amd64 does not
have some IEEE FP functions like fpresetsticky(). The build
failure log is now available at
http://pointyhat.freebsd.org/errorlogs/amd64-5-full/gnuplot371+-1.2.0_1.log
I found file/patch-za causes the problem. The feature of
this patch as reported in ports/16120 can take effect only
on FreeBSD/i386.
PR: ports/69143
Submitted by: NAKAJI Hiroyuki <nakaji@jp.freebsd.org>