THRIFT-5295 - makeThread and ThreadFactory extensible

[rglarix]

Signed-off-by: rglarix rglarix@users.noreply.github.com

THRIFT-5295: This patch for cpp makes Thread and ThreadFactory customizable

• Did you create an Apache Jira ticket? (not required for trivial changes)
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[rglarix]

Sorry, CI fails but it seems an appveyor problem still in the setup phase:
[00:01:11] downloading mingw-w64-x86_64-libevent-2.1.10-1-any.pkg.tar.xz...
[00:01:11] error: failed to commit transaction (unexpected error)
[00:01:11] Errors occurred, no packages were upgraded.
[00:01:11] Command exited with code 1

Something similar with travis, compilation of cpp was fine, I just cannot understand why it fails.

[Jens-G]

Could you give this one more try and force push, so a new CI run gets triggered?

[rglarix]

done!