RFR (XS): 8025233: Move sun.invoke.Stable into java.lang.invoke package

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/8025233/webrev.00/
2 lines changed: 0 ins; 0 del; 2 mod

Move sun.invoke.Stable into java.lang.invoke package and make it 
package-private to reduce visibility. This request covers hotspot part 
of the fix.

Testing: unit tests on @Stable, octane

Thanks!

Links:
   https://bugs.openjdk.java.net/browse/JDK-8025233

Best regards,
Vladimir Ivanov