C2 compare and swap fixes

[Roman Kennke]

Am Montag, den 06.06.2016, 11:01 +0200 schrieb Roland Westrelin:
> Hi Roman,
> 
> As you suggested, I reverted some of the changes to library_call.cpp
> that are not longer necessary:
> 
> http://cr.openjdk.java.net/~roland/shenandoah-cas/webrev.01/

Ok for me to commit.

Roman