RFR: 8247908: Replace IsRegisteredEnum with std::is_enum

[Thomas Schatzl]

Hi,

On 23.07.20 09:27, Kim Barrett wrote:
> Please review this change which removes our IsRegisteredEnum type
> trait and its uses, instead using the std::is_enum<> type trait.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8247908
> 
> Webrev:
> https://cr.openjdk.java.net/~kbarrett/8247908/open.00/
> 
> Testing:
> mach5 tier1
> 

   lgtm.

Thomas