A global uno::Sequence object is a little problematic in that in its dtor
uno::Sequence looks up the types of its contained objects to do correct release
on them. This needs the cppu infrastructure to be working, but that's rather
problematic at shut-down time where there's some nasty life-cycle issues in cppu. 

Currently the cppu foo leaks, so this isn't a noticeable issue, but a leaking
cppu causes the threads used by e.g. unopkg to not exit correctly and outlive
process exit and eventual destruction of all used data.

For sax, the whole issue could be side-stepped by using rtl::BytesSequences and
toUnoSequence which is a simple inline cast, so no detrimental performance issue
should exist.