RFR: 8367603: Optimize exact division in BigDecimal [v16]

[fabioromano1]

> A formula to lower the overestimate for the precision of an exact quotient, without introducing too expensive operations of division on numerator and denominator.

fabioromano1 has updated the pull request incrementally with three additional commits since the last revision:

 - Code simplification
 - Avoid overflow of result's scale
 - Review's suggestions

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27271/files
  - new: https://git.openjdk.org/jdk/pull/27271/files/e94592a1..61fce13e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27271&range=15
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27271&range=14-15

  Stats: 102 lines in 2 files changed: 48 ins; 43 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/27271.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27271/head:pull/27271

PR: https://git.openjdk.org/jdk/pull/27271