message: Fix bitcast between types of different column counts
diff: @@ -1310,7 +1310,6 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
  var.type = type.scalar().Type();
  var.columns = type.vector().count & 0xff;
  - var.value = ShaderValue();
  }
  SetDst(cast.result, var);
  