Assume fast unaligned access on WebAssembly
Assume fast unaligned access on WebAssembly

I saw this tweet claiming this flag makes libdeflate run 20% faster on
WebAssembly: https://twitter.com/Algunenano/status/1317098341377900550.

Indeed, when tried even in a complex PNG compression benchmark I've
observed 10-15% improvement when this flag is enabled.

Even though WebAssembly might be running on top of a variety of
underlying platforms, the spec requires it to support unaligned access,
and on majority of platforms it will translate to a faster code.

Hence, I think it makes sense to enable this flag by default.

ebiggers/libdeflate,ebiggers/libdeflate,ebiggers/libdeflate