Add -fPIC to CFLAGS; bump PORTREVISION

PIC is required for this port to work properly. However, the
port's own build system only adds it if CFLAGS is not set in MAKE_ENV.
This adds -fPIC to the pre-defined set of CFLAGS to ensure the port
is properly built.

PR: 208201
Submitted by: tphilipp@potion-studios.com (maintainer)