Auto merge of rust-lang#103231 - ecnelises:le_fix, r=lcnr

Remove byte swap of valtree hash on big endian

This addresses problem reported in rust-lang#103183. The code was originally introduced in rust-lang@e14b34c. (see rust-lang#96591)

On big-endian environment, this operation sequence actually put the other half from 128-bit result, thus we got different hash result on LE and BE.

Author: bors