Trace control with trace subroutine calls

The controls for the trace routine are available as subroutines from the librts.a library.

The subroutines return zero on successful completion. The subroutines are:

int trcon()

Begins or resumes collection of trace data.

int trcoff()

Suspends collection of trace data.

int trcstop()

Stops collection of trace data and terminates the trace routine.

int trcstart()

Starts a trace session.