[code-reflection] RFR: HAT memory mallocs and copies improved [v2]

[Juan Fumero]

> Use of `MappableIface` annotations to tag the buffer accessor for OpenCL. 
> In addition, this PR reuses buffers attach to each dispatch and copies the data that is needed. 
> 
> For OpenCL and macOS, this PR in HAT increases performance of up to 30% end-to-end time (including data movement).
> 
> Buffer accessors are not available for CUDA, but the CUDA runtime in HAT minimizes the transfers as well as cuda allocations. 
> 
> How to test? All unit-tests should be passing:
> 
> 
> java @hat/test-suite ffi-opencl
> 
> 
> Run violajones:
> 
> 
> HAT=MINIMIZE_COPIES java -cp hat/job.jar hat.java run ffi-opencl -Dheadless=true violajones
> ``` 
> 
> Run GoL:
> 
> 
> java @hat/run ffi-opencl life

Juan Fumero has updated the pull request incrementally with one additional commit since the last revision:

  [hat] life-example revert control to RO

-------------

Changes:
  - all: https://git.openjdk.org/babylon/pull/746/files
  - new: https://git.openjdk.org/babylon/pull/746/files/654d1b53..fe11189a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=746&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=746&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/babylon/pull/746.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/746/head:pull/746

PR: https://git.openjdk.org/babylon/pull/746