RFR: JDK-8222079: Don't use memset to initialize fields decode_env constructor in disassembler.cpp

[Roman Kennke]

Ping?

Thanks,
Roman


> Recent gcc (I use version 9) complains about using memset to initialize 
> fields of decode_env. Let's use proper field initializers instead.
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8222079
> Webrev:
> http://cr.openjdk.java.net/~rkennke/JDK-8222079/webrev.01/
> 
> Can I please get a review?
> 
> Thanks, Roman