message: Add $cpu variable to filters
diff: @@ -1575,6 +1575,11 @@ const char *filter_get_keyval_func( trace_info_t *trace_info, const trace_event_
  snprintf_safe( buf, "%.6f", event->ts * ( 1.0 / NSECS_PER_MSEC ) );
  return buf;
  }
  + else if ( !strcasecmp( name, "cpu" ) )
  + {
  + snprintf_safe( buf, "%u", event->cpu );
  + return buf;
  + }
  else if ( !strcasecmp( name, "duration" ) )
  {
  if ( event->duration == ( uint32_t )-1 )
  @@ -2340,7 +2345,7 @@ bool TraceWin::render()
  tooltip += s_textclrs().bright_str( "Event Filter\n\n" );
  tooltip += "Vars: Any field in Info column plus:\n";
  - tooltip += " $name, $comm, $user_comm, $id, $pid, $tgid, $ts, $duration\n";
  + tooltip += " $name, $comm, $user_comm, $id, $pid, $tgid, $ts, $cpu, $duration\n";
  tooltip += "Operators: &&, ||, !=, =, >, >=, <, <=, =~\n\n";
  tooltip += "Examples:\n";
  