Don't do unaligned accesses

Avoid unaligned accesses as those can fail on older ARM chips.

Note: This is part of a set of changes which are required to get test suite & unit tests passing on ARM GDC. All necessary changes for GDC are here for reference:
https://github.com/jpf91/GDC/commits/arm-old

Once these pull requests are merged upstream I'll merge them into GDC as well.