RFR: 8301578: Perform output outside synchronization in Module.class [v2]

[Per Minborg]

> This PR proposed to reduce contention in synchronized methods mainly by doing I/O operations outside synch blocks.

Per Minborg has updated the pull request incrementally with two additional commits since the last revision:

 - Update after comments
 - Remove warning

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12193/files
  - new: https://git.openjdk.org/jdk/pull/12193/files/cdd3ac4c..9af658b1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12193&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12193&range=00-01

  Stats: 13 lines in 2 files changed: 8 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/12193.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12193/head:pull/12193

PR: https://git.openjdk.org/jdk/pull/12193