BUG/MEDIUM: dns: fix alignment issue when building DNS queries

BUG/MEDIUM: dns: fix alignment issue when building DNS queries

On some architectures, unaligned access is not authorized. On most
architectures, it is just slower. Therefore, we have to use memcpy()
when an unaligned access is needed, specifically when writing the qinfo.

Also remove the unaligned access when reading answer count when reading
the answer. It's likely that this instruction was optimized away by the
compiler since it is unneeded. Add a comment to explain why we use 7 as
an offset instead of 6. Not an unaligned offset since "resp" is
"unsigned char", then promoted to int.