[crac] RFR: Report checkpoint processing to jcmd [v26]

[Ilarion Nakonechnyy]

> pass output stream from diagnosticCommand.cpp through java code into os_linux.cpp::VM_crac::doit()

Ilarion Nakonechnyy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 50 additional commits since the last revision:

 - Merge branch 'pr-10' into crac
 - Rename stream to jcmd as the only possible
 - Fix another whitespace problem
 - fixup! Fix style a bit
 - Print whole exception to jcmd, as for API
 - fixup! Refactor a bit around linux attach
 - Fix assert on checkpointRestore API call
 - fixup! Fix style a bit
 - Refactor a bit around linux attach op
   
   * narrow the interface of LinuxAttachListener and make it more
     consistent
   * only LinuxAttachOp can float on Linux
   * rename to current_op
 - Fix style a bit
 - ... and 40 more: https://git.openjdk.org/crac/compare/217d5bc6...72b8cdb2

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

Changes:
  - all: https://git.openjdk.org/crac/pull/10/files
  - new: https://git.openjdk.org/crac/pull/10/files/2dc03844..72b8cdb2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=10&range=25
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=10&range=24-25

  Stats: 2956 lines in 68 files changed: 2581 ins; 186 del; 189 mod
  Patch: https://git.openjdk.org/crac/pull/10.diff
  Fetch: git fetch https://git.openjdk.org/crac pull/10/head:pull/10

PR: https://git.openjdk.org/crac/pull/10