Build Warnings Related to Spectre Mitigation

[nibanks]

With the latest release, most build warnings went away, except for the following:

https://github.com/nibanks/msh3/actions/runs/3868034900/jobs/6593213121#step:7:118

D:\a\msh3\msh3\ls-qpack\deps\xxhash\xxhash.c(461): warning C5045: Compiler will insert Spectre mitigation for memory load if /Qspectre switch specified [D:\a\msh3\msh3\build\ls-qpack\ls-qpack.vcxproj]
D:\a\msh3\msh3\ls-qpack\deps\xxhash\xxhash.c(458): message : index 'p' range checked by comparison on this line [D:\a\msh3\msh3\build\ls-qpack\ls-qpack.vcxproj]
D:\a\msh3\msh3\ls-qpack\deps\xxhash\xxhash.c(461): message : feeds call on this line [D:\a\msh3\msh3\build\ls-qpack\ls-qpack.vcxproj]
...

[nibanks]

Oh, I found one other warning (not spectre related):
https://github.com/nibanks/msh3/actions/runs/3868034900/jobs/6593213177#step:7:114

D:\a\msh3\msh3\ls-qpack\lsqpack.c(4222,5): warning C4061: enumerator 'LQRHS_ERROR' in switch of enum 'lsqpack_read_header_status' is not explicitly handled by a case label [D:\a\msh3\msh3\build\ls-qpack\ls-qpack.vcxproj]
D:\a\msh3\msh3\ls-qpack\lsqpack.h(340,6): message : see declaration of 'lsqpack_read_header_status' [D:\a\msh3\msh3\build\ls-qpack\ls-qpack.vcxproj]