RFR: 8311661: Resolve duplicate symbol of StringTable::StringTable with JDK static linking

[Jiangli Zhou]

Move StringTable to JavaClassFile namespace.

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Commit messages:
 - Move  '} // namespace JavaClassFile' to after '#endif //INCLUDE_CDS_JAVA_HEAP'.
 - 8311661: Resolve duplicate symbol of StringTable::StringTable with JDK static linking

Changes: https://git.openjdk.org/jdk/pull/14808/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14808&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311661
  Stats: 59 lines in 21 files changed: 14 ins; 0 del; 45 mod
  Patch: https://git.openjdk.org/jdk/pull/14808.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14808/head:pull/14808

PR: https://git.openjdk.org/jdk/pull/14808