[code-reflection] Integrated: Hat performance minimize buffer copy tweaking

[Gary Frost]

Buffer marking seems to work

Get perf improvement on game of life (x2.5) mandel (x0.25 ish) and suprisingly on violajones. 

To compare with and without use env vars 


HAT=GPU,MINIMIZE_COPIES java @bldr/hatrun ffi-opencl life

vs 

HAT=GPU java @bldr/hatrun ffi-opencl life

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

Commit messages:
 - Buffer marking seems to work.
 - Added seven seg to mandel
 - Added TRACE_ENQUEUES to allow us to show the effect of MINIMIZE_COPIES

Changes: https://git.openjdk.org/babylon/pull/348/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=348&range=00
  Stats: 653 lines in 11 files changed: 370 ins; 224 del; 59 mod
  Patch: https://git.openjdk.org/babylon/pull/348.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/348/head:pull/348

PR: https://git.openjdk.org/babylon/pull/348