Squashing i386 tests and fix#785

mkitti wants to merge 4 commits intozarr-developers:mainzarr-developers/numcodecs:mainfrom

mkitti:mkitti-i386-zstd-frame-content-size-ull-mergedmkitti/numcodecs:mkitti-i386-zstd-frame-content-size-ull-mergedCopy head branch name to clipboard