RFR: 8356891: Some code simplifications in BigInteger [v23]

[fabioromano1]

> Some changes in `Biginteger`s' bit operations that increase the code readability and slightly optimize the execution time.

fabioromano1 has updated the pull request incrementally with one additional commit since the last revision:

  Removed needless condition
  
  Co-authored-by: Raffaello Giulietti <raffaello.giulietti at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25166/files
  - new: https://git.openjdk.org/jdk/pull/25166/files/eb3834e3..60d3c1f9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25166&range=22
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25166&range=21-22

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25166.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25166/head:pull/25166

PR: https://git.openjdk.org/jdk/pull/25166