Fix unaligned memory accesses as reported by ASan

e.g. runtime error: store to misaligned address 0x7ffec33195e3 for type
'short int', which requires 2 byte alignment

These aren't a problem for x86, but could be a problem for some other CPU
architectures that don't support unaligned access. I didn't use memcpy() to
resolve this (though that would've worked) to make this change endian agnostic.