Implement the lockstat provider using SDT(9) instead of the custom provider

in lockstat.ko. This means that lockstat probes now have typed arguments and
will utilize SDT probe hot-patching support when it arrives.

Reviewed by:	gnn
Differential Revision:	https://reviews.freebsd.org/D2993


git-svn-id: svn+ssh://svn.freebsd.org/base/head@285703 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f