• Copy graphics/geos at version 3.5 to graphics/geos35

This is needed to fix osm2pgsql which is not compatible with geos
3.6.

For this purpose, the port was simplified (unneeded options and
files removed) and conflicts with graphics/geos were resolved
(includes placed under include/geos35, libraries renamed to
libgeos35.{a,so}, geos-config renamed to geos-config35). The
library behaves correct wrt SONAME, as it points to libgeos-${PORTVERSION}.so