[11u] RFR 8262739: String inflation C2 intrinsic prevents insertion of anti-dependencies

[Zhengyu Gu]

I would like to backport this patch to 11u for parity with Oracle 
11.0.12-oracle.

The original bug: https://bugs.openjdk.java.net/browse/JDK-8262739
The original patch: https://github.com/openjdk/jdk/commit/3caea470

The original patch does not apply cleanly, due to slight different 
context with 11u, as it does not have 
"!strcmp(_matrule->_rChild->_opType,"VectorMaskGen")||" line in 
formssel.cpp.

11u webrev: http://cr.openjdk.java.net/~zgu/JDK-8262739-11u/webrev.00/

Test:
   Passed new test in patch.

Thanks,

-Zhengyu