RFR: 8272576: G1: Use more accurate integer type for collection set length

[Albert Mingkun Yang]

On Tue, 17 Aug 2021 16:12:28 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple change of using smaller integer type, `size_t` to `uint`. Also moved the bound-check assertion before array access.
> 
> Test: hotspot_gc

Thanks for the review.

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

PR: https://git.openjdk.java.net/jdk/pull/5148