RFR: 8289006: Cleanup from thread.hpp split [v2]

[Coleen Phillimore]

> Remove extra include directives.  Tested with GHA.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  remove redundant include

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9252/files
  - new: https://git.openjdk.org/jdk/pull/9252/files/f3e109c8..1a249ab4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9252&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9252&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9252.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9252/head:pull/9252

PR: https://git.openjdk.org/jdk/pull/9252