[15] RFR (L) 8235825: C2: Merge AD instructions for Replicate nodes

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/jbhateja/8235825/webrev.00/all/
https://bugs.openjdk.java.net/browse/JDK-8235825

Merge AD instructions for the following vector nodes:
   - ReplicateB, ..., ReplicateD

Individual patches:
 
http://cr.openjdk.java.net/~vlivanov/jbhateja/8235825/webrev.00/individual

Testing: tier1-4, test run on different CPU flavors (KNL, CLX)

Contributed-by: Jatin Bhateja <jatin.bhateja at intel.com>
Reviewed-by: vlivanov, sviswanathan, ?

Best regards,
Vladimir Ivanov