Move safememcpy() to util.c so it doesn't get inlined.

Move safememcpy() to util.c so it doesn't get inlined.

It appears that some C compilers will inline safememcpy() *and* will, as
a result, optimize to assume alignment it if it's passed a
putatively-aligned pointer. As the pointers in question are not
guaranteed to be aligned, that can cause crashes on, for example, SPARC.

Also, rename the function to unaligned_memcpy(), to clarify what's
"safe" about it, and change some direct memcpy() calls to use it as
well.