Remove the DTrace printt and typeref actions.

Remove the DTrace printt and typeref actions.

These are FreeBSD-specific and were added in r178576 to provide the ability
to pretty-print instances of compound types. However, the print action has
long since been augmented to provide this functionality with a simpler
interface.

Discussed with:	gnn
Differential Revision:	https://reviews.freebsd.org/D8478