[crac] RFR: 8376959: [CRaC] Turn simengine into shared library [v3]

[Radim Vansa]

> Right now `simengine` is implemented as an executable, invoked through `libcrexec` that implements the C/R API. Since the programmatic C/R API should be the main interface, any exec API is redundant; let's turn `simengine` into shared (dynamic) library implementing the API on its own.
> 
> The `pauseengine` does not need to exist on its own; this can be only an option `pause=true` for `simengine`. The implementation is Linux only (and it is out of scope to fill in a non-Linux implementation - the `pause` option can be just excluded in non-Linux `libsimengine`).
> 
> We expect to turn `libcrexec` + `criuengine` into `libcriuengine` in a follow up (not as part of this issue).

Radim Vansa has updated the pull request incrementally with one additional commit since the last revision:

  Fixups

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

Changes:
  - all: https://git.openjdk.org/crac/pull/289/files
  - new: https://git.openjdk.org/crac/pull/289/files/1ea5ad88..fbd07e66

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=289&range=02
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=289&range=01-02

  Stats: 27 lines in 3 files changed: 16 ins; 6 del; 5 mod
  Patch: https://git.openjdk.org/crac/pull/289.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/289/head:pull/289

PR: https://git.openjdk.org/crac/pull/289