Add support for int-to-short in the optimizing compiler.

- Add support for the int-to-short Dex instruction in the
  optimizing compiler.
- Generate x86, x86-64 and ARM (but not ARM64) code for
  byte to short, int to short and char to short
  HTypeConversion nodes.
- Add related tests to test/422-type-conversion.

Change-Id: If1829549708d9c3473efaa641f7f0bcfa6080ae9
5 files changed