Woff2 decoding crashes on alignment critical architectures

[MartinHusemann]

Use memcpy() instead of dereferencing casted pointers where thecast increases alignment requirements and causes crashes on some architectures.

[jbeich]

@rsheeter, can you take a look since you've added ea4c87a? The issue blocks Firefox on sparc64 (Linux, NetBSD) from working.

[rsheeter]

Hm. In poking through I believe this was done [not by me] during perf tuning. I need to ask around internally a bit.

[MartinHusemann]

Thanks for checking!
I would be slightly surprised if it would create different object code with any modern compiler on architectures where the alignment does not matter.