RFR(trivial): 8230037: Confused MetaData dumped by PrintOptoAssembly

[Jie Fu]

Hi all,

JBS:    https://bugs.openjdk.java.net/browse/JDK-8230037
Webrev: http://cr.openjdk.java.net/~jiefu/8230037/webrev.00/

People may get confused with the 'MetaData' dumped by PrintOptoAssembly.
For detailed info, please see the JBS.
It might be better to make it more clear.

Testing:
  - make test TEST="test/hotspot/jtreg:tier1" CONF=fastdebug on Linux/x64
  - make test TEST="tier1"                    CONF=release   on Linux/x64

Thanks a lot.
Best regards,
Jie