RFR: 8339934: Simplify Math.scalb(double) method

[Raffaello Giulietti]

On Wed, 11 Sep 2024 12:45:50 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

> `Math.scalb(double)` can be simplified, removing a loop and using larger/smaller factors.

The proposed implementation is even about 1.5x faster, but that's not the point of this PR.
The point is to have simpler logic.
Similar logic could be adopted for the `float` case as well.

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PR Comment: https://git.openjdk.org/jdk/pull/20948#issuecomment-2343578028