Remove unaligned functions, since most function support unaligned memory now.  This reduces complexity and improves performance for unaligned cases because C code can be avoided, and overhead is less.  Downside is old cpus (core2 and earlier) will be slower for aligned memory case. Except mips, which has alignment requirement, but remove unaligned variant.
BUG=365
TESTED=unittest builds and passes locally
R=harryjin@google.com

Review URL: https://webrtc-codereview.appspot.com/24839004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1113 16f28f9a-4ce2-e073-06de-1de4eb20be90