RFR: 8341470: BigDecimal.stripTrailingZeros() optimization [v7]

[fabioromano1]

> An optimized algorithm for `BigDecimal.stripTrailingZeros()` that uses repeated squares trick.

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

 - Removed old exp declaration
 - Moved exp declaration

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21323/files
  - new: https://git.openjdk.org/jdk/pull/21323/files/1ed24c58..955a623c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21323&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21323&range=05-06

  Stats: 4 lines in 1 file changed: 2 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21323.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21323/head:pull/21323

PR: https://git.openjdk.org/jdk/pull/21323