RFR: 8286028: Some -Xlint keys are missing in javac man page

[Jonathan Gibbons]

Please review an update to the javac man page, derived from the upstream sources, and triggered by PR #7971 by Ethan McCue.

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Commit messages:
 - JDK-8282149: Some -Xlint keys are missing in javac man page

Changes: https://git.openjdk.java.net/jdk/pull/8507/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8507&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286028
  Stats: 20 lines in 1 file changed: 14 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8507.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8507/head:pull/8507

PR: https://git.openjdk.java.net/jdk/pull/8507