Lock Giant in postsig() for the KTRACE case as ktrpsig() needs Giant when it writes out to the trace file.
Lock Giant in postsig() for the KTRACE case as ktrpsig() needs Giant when
it writes out to the trace file.

Reported by:	peter, gallatin, and others

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase