Use make_unique_xstrdup in tracepoint

Use make_unique_xstrdup in tracepoint

This changes the tracepoint code to use make_unique_xstrdup (and
make_unique_xstrndup).  This meant changing the types of some members
of uploaded_tp -- but it seems to me that using array types there did
not add any value.

Approved-By: Andrew Burgess <aburgess@redhat.com>