am 5b81b918: libc: optimize memmove() with memcpy() if possible.

Merge commit '5b81b918173b4bf446c1a85240c094e4dd77231f' into gingerbread-plus-aosp

* commit '5b81b918173b4bf446c1a85240c094e4dd77231f':
  libc: optimize memmove() with memcpy() if possible.