RFR(S): 8240195: some jaotc failures of fastdebug build with specific flags

[Roland Westrelin]

> I tried your patch and I can confirmed that your patch works. 
> One cosmetic thing is there're 2 whitespaces in your change of subtypenode.cpp.

Thanks. I'll fix that.

> It's hard to eyeball those style things in webrev.  Can we use clang-format to enforce C++ coding style? 
> I can file a JBS issue and define some basic rules like the position of pointer etc. 

That would have to be discussed with a wider audience first, I
think. Maybe bring it up on hotspot-dev?

Roland.