[ARM] Move the implementation of the target hooks related to copy-related
instruction from ARMInstrInfo to ARMBaseInstrInfo.
That way, thumb mode can also benefit from the advanced copy optimization.

<rdar://problem/12702965>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216274 91177308-0d34-0410-b5e6-96231b3b80d8