devel/libthai: Bump PORTREVISION to force package rebuild

Because of libdatrie changes, libthai also needs to be rebuilt,
otherwise libthai does not get updated and, for example, xfce4
can not start with the error:

/usr/local/lib/libdatrie.so.1: version DATRIE_0.2 required
by /usr/local/lib/libthai.so.0 not defined

And also assume MAINTAINER