message: Fix implementation of OpSelect
diff: @@ -728,13 +728,11 @@ void ThreadState::StepNext(ShaderDebugState *state,
  }
  else
  {
  - ShaderVariable var = GetSrc(select.object1);
  - ShaderVariable b = GetSrc(select.object2);
  for(uint8_t c = 0; c < cond.columns; c++)
  {
  if(cond.value.uv[c] == 0)
  {
  - if(VarTypeByteSize(var.type))
  + if(VarTypeByteSize(var.type) == 8)
  var.value.u64v[c] = b.value.u64v[c];
  else
  var.value.uv[c] = b.value.uv[c];
  