Fix clamped capacity to be divided by element size

[jkugelman]

Fixes https://github.com/Geal/nom/issues/1459#issuecomment-1244461213: the capacity of a Vec<O> is measured in number of elements not number of bytes, so divide 64KiB by the element size. This will round towards 0, which is desirable.

[coveralls]

Coverage increased (+0.007%) to 79.285% when pulling 64216b897f572ff698950fb4c023f252d961f32d on jkugelman:clamp-capacity-wording into 3645656644e3ae5074b61cc57e3f62877ada9190 on Geal:main.

[coveralls]

Pull Request Test Coverage Report for Build 3796644783

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 61.637%

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Files with Coverage Reduction	New Missed Lines	%
src/character/complete.rs	1	81.02%
<!--	Total:	1

Totals
Change from base Build 3796631867:	-0.01%
Covered Lines:	1499
Relevant Lines:	2432

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💛 - Coveralls

[Geal]

thanks!