Tracepoint API change: combine TP_PROTO and TP_VARS into TP_ARGS, remove _NOARGS...

New API for tracepoints, combining the TP_PROTO and TP_VARS arguments
into a single "TP_ARGS" macro. It takes up to 10 parameters (from 0 to
10). The "_NOARGS" special-case is not needed anymore: it can be
achieved simply by passing an empty TP_ARGS:

  TP_ARGS(),

to the standard tracepoint event declarations.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>