[Support] Don't include <algorithm> in Hashing.h

The include is for std::swap(), but that's in <utility> in C++11,
and Hashing.h already includes that.

Differential Revision: https://reviews.llvm.org/D100657

GitOrigin-RevId: ef620c40f371e7e3269bd8bef57d069330baa355
1 file changed