RFR: 8217325: Enable inlining of java_lang_Class::oop_size_raw

[Claes Redestad]

Hi,

InstanceMirrorKlass::oop_size could be helped slightly if
java_lang_Class::oop_size_raw was made inlineable.

This significantly speeds up one branch in oopDesc::size_given_klass
(heavily used by G1, at least during startup/warmup) while not causing
any increase in binary size (linux x64).

Bug:    https://bugs.openjdk.java.net/browse/JDK-8217325
Webrev: http://cr.openjdk.java.net/~redestad/8217325/open.00/

Testing: tier1-2 (complete)

Thanks!

/Claes