RFR: Fix assertion error with advance promotion budgeting

[Roman Kennke]

On Mon, 31 Oct 2022 14:31:49 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

> Round-off errors were resulting in an assertion error.  Budgeting calculations are "complicated" because only regions that are fully empty may be loaned from old-gen to young-gen.  This change recalculates certain values during budgeting adjustments that follow collection set selection rather than endeavoring to make changes to the values computed before collection set selection.  The API is simpler as a result.

Looks ok to me.

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Marked as reviewed by rkennke (Lead).

PR: https://git.openjdk.org/shenandoah/pull/165