graphics/opencv: fix configure when EIGEN is off

When EIGEN option is off, CMAKE_ARGS is reset, thus enabling build of
tests and docs (causing some leftovers), and, should it be installed,
linking against libdc1394 even when option DC1394 is off. PORTREVISION
bump is needed to address the latter case.

Meanwhile, re-enable make jobs.

Differential Revision: https://reviews.freebsd.org/D2893
Reviewed by: jhale (maintainer)
Approved by: jhale (maintainer)
MFH: 2015Q2