Fix unaligned loads in metrohash
Fix unaligned loads in metrohash

Unaligned loads are undefined behavior in C++. Using a memcpy to get the
value results in the same instructions (a single mov) on x86, even with -O1
only, msvc needs /O2.

Change-Id: I805ccaeeb552719df9de732364de78cb6f248e63

GPUOpen-Drivers/MetroHash,GPUOpen-Drivers/MetroHash