A char array copy optimization.

- Based on measurements, copy char by char for arrays of length <= 64.
- With this change, the Ritz MemAllocBench got ~25% faster on Nexus 4
  and ~20% faster on host.
- This change only handles arraycopy calls in the core libraries and
  char arrays with the rest future work.

Bug: 7103825
Change-Id: Ie88890eb65f011ca052b1f253f1b0e078ec24b6b
1 file changed