MFH: r463298

math/ogdf: unbreak build with Clang 6 (C++14 by default)

The bundled version of CoinMP required the same patches as those applied
to the port math/coinmp, so the patches were copied from there.

Submitted by: jbeich (via commit r458136)
Reported by: antoine (via bug 224669)

Approved by: ports-secteam blanket