fix Issue 24390 - AssertError@src/dmd/backend/cgxmm.d(1476): Assertion failure

[ibuclaw]

This is tickled by #16173, so not actually in any released version of the compiler.

As far as I can tell, the inliner reverts integer promotions by casting from int -> short -> char, the latter type is invalid for vectors. Instead, do cast from int -> short -> byte.

[dlang-bot]

Thanks for your pull request, @ibuclaw!

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Testing this PR locally

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dub run digger -- build "master + dmd#16181"

[thewilsonator]

as per the bot, please retitle the commit message "Fix bugzilla issue 24390 - ..."

otherwise looks good