RFR: 8290079: Reduce interaction with volatile in static initializer of BigInteger [v2]

[Сергей Цыпанов]

> `BigInteger.powerCache` is volatile and should be assigned only once in static initializer.

Сергей Цыпанов has updated the pull request incrementally with one additional commit since the last revision:

  8290079: Rename local var

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9451/files
  - new: https://git.openjdk.org/jdk/pull/9451/files/15971c4c..1f51992b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9451&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9451&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/9451.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9451/head:pull/9451

PR: https://git.openjdk.org/jdk/pull/9451