Xtensa updates for 2.3:

- fix cross-page opcode handling;
- move window overflow exception generation decision to translation phase;
- don't generate dead code after privilege, window overflow or coprocessor
  exception;
- add monitor command 'info opcount' for dumping TCG opcode counters.

# gpg: Signature made Wed 17 Dec 2014 02:57:01 GMT using RSA key ID F83FA044
# gpg: Good signature from "Max Filippov <max.filippov@cogentembedded.com>"
# gpg:                 aka "Max Filippov <jcmvbkbc@gmail.com>"

* remotes/xtensa/tags/20141217-xtensa:
  target-xtensa: don't generate dead code
  target-xtensa: record available window in TB flags
  target-xtensa: test cross-page opcode
  target-xtensa: fix translation for opcodes crossing page boundary
  tcg: add separate monitor command to dump opcode counters

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>