RFR (M) 8035605: Expand functionality of PredictedIntrinsicGenerator

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8035605/webrev
https://bugs.openjdk.java.net/browse/JDK-8035605

Expand functionality of PredictedIntrinsicGenerator to allow several 
predicates and separate intrinsic codes per intrinsified (virtual) 
method. We need this for 8035968: C2 support for SHA on SPARC.

Renamed "predicted" intrinsics to "predicated" intrinsics which is more 
correct.

Moved null_check to callGenerator.cpp to simplify predicated intrinsics.

Fixed LibraryCallKit::load_field_from_object() to load from primitive 
type fields.

Fixed broken GraphKit::merge_memory() to allow merge more than 2 paths. 
Currently it works because only 2 paths are merged in places where it is 
used.

Tested with jtreg, JDK control build in JPRT with jdk jtreg testing 
which includes crypto tests. Also tested with applied 8035968 SHA 
changes. 8035968 will add new jtreg TestSHA test which was also used for 
testing.

Thanks,
Vladimir