Clean up, minor options fixes and shuffling.

• drop -ffast-math from the compiler flags [1]
• drop libc++ hacks for FreeBSD 9.x/10.1 and use the new gcc-c++11-lib [2]
• be sure to optimize for packaging when PACKAGE_BUILDING [3]
• simplify CMake OPTION_OMP passing [2]
• bump PORTREVISION

Reported by: Ingo Weyrich [1], jbeich@ [2], DrSlony