RFR: 8230808: Remove Access::equals()

[Per Liden]

Access::equals() is not specialized by any barrier set and can be 
removed. This patch doesn't remove oopDesc::equals()/equals_raw(), but 
they don't use Access::equals() to do the work anymore. Removing 
oopDesc::equals() is a more intrusive change, which can be done as the 
next step.

Bug: https://bugs.openjdk.java.net/browse/JDK-8230808
Webrev: http://cr.openjdk.java.net/~pliden/8230808/webrev.0

/Per