message: Remove ctx for entire thread lifetime
diff: @@ -116,7 +116,6 @@ thread_proc( void *arg )
  unsigned int seed = gettid();
  gpuvis_set_thread_name( "thread_%d", tid );
  - gpuvis_trace_begin_ctx_printf( tid, "thread_%d running", tid );
  while ( running )
  {
  @@ -128,7 +127,6 @@ thread_proc( void *arg )
  usleep( 1000 );
  }
  - gpuvis_trace_end_ctx_printf( tid, "thread_%d end running", tid );
  return 0;
  }
  