RFR: 7903470 jtreg AgentServer log() does not flush

[Ludvig Janiuk]

Please review this change to start flushing logs on every message in AgentServer.

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Commit messages:
 - whitespace
 - Flush logs in AgentServer

Changes: https://git.openjdk.org/jtreg/pull/156/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=156&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903470
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/156.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/156/head:pull/156

PR: https://git.openjdk.org/jtreg/pull/156