RFR: 8276571: C2: pass compilation options as structure [v2]

[Vladimir Kozlov]

> Currently we pass several compilation options as separate arguments to `Compile`: 
> 
> Compile C(env, target, entry_bci, subsume_loads, do_escape_analysis, eliminate_boxing, do_locks_coarsening, install_code, directive); 
> 
> Originally we had only `subsume_loads` option but we added few since then and we may add more. 
> 
> I suggest to add new `Options` class to pass these values into `Compile`.

Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6237/files
  - new: https://git.openjdk.java.net/jdk/pull/6237/files/34f29c8d..d2490eb4

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6237&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6237&range=00-01

  Stats: 12 lines in 2 files changed: 8 ins; 2 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6237.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6237/head:pull/6237

PR: https://git.openjdk.java.net/jdk/pull/6237