This port needs USES=compiler:c++11-lang to build on GCC-based
architectures.

To build on powerpc* platforms, -DBIG_ENDIAN must be defined.

While here, add USES=gnome, simplify by using localbase, and pet
portlint.

PR: 234226
Submitted by: Piotr Kubaj
Approved by: portmgr (tier-2 blanket)