It's unclear why c2 needs to be set after an entity reference.

This is a bit slower since we don't pass n_xml_buf as an argument but
rather get it with a call to wcslen. It is much cleaner though, since
the name ProcessSsmlTag() implies that all processing should be done
there.

This avoids 'unused parameter' errors in readclause.c.

The only entry point in the file is ProcessSsmlTags().

use parameters instead of globals