stdsimd-verify failures

[gnzlbg]

It seems that syn fails to parse the following files: "cpuid", "xsave", "bswap", then the script fails to find functions like: _bextr_u32, and then the script hits rust-lang/rust#48923 :/

[alexcrichton]

This is likely rust-lang/rust#49596, fixed in rust-lang/rust#49597