[vector] unify load/store tests

[Paul Sandoz]

Hi,

Here is an updated patch for unifying load/store. This is merged with the load/store tests.

  http://cr.openjdk.java.net/~psandoz/panama/unify-load-store/webrev/

- The relative buffer accessors are removed.

- The load/store intrinsics take a base + address for intrinsic access and a container + index for default access.

- Related methods were made abstract or final on the public primitive vectors.

- Redundant casts were removed from the implementation.

- Type variable names of intrinsic methods were changed for those that accept a Vector or Mask (alas we cannot represent this in the type system unless Vector and Mask share are common super type other than Object).

All tests pass locally for me in fast debug mode with -XX:+UseVectorApiIntrinsics -XX:-TieredCompilation.

Thanks,
Paul.