Merge remote-tracking branch 'remotes/xtensa/tags/20180918-xtensa' into staging

target/xtensa updates:

- fix gdbstub register counts;
- add big-endian core test_kc705_be;
- convert to do_transaction_failed and add test for failed memory
  transactions;
- fix couple FPU2000 bugs;
- fix s32c1i implementation;
- clean up exception handlers generation in xtensa tests;
- add support for semihosting console input through a chardev.

# gpg: Signature made Tue 18 Sep 2018 18:35:50 BST
# gpg:                using RSA key 51F9CC91F83FA044
# gpg: Good signature from "Max Filippov <filippov@cadence.com>"
# gpg:                 aka "Max Filippov <max.filippov@cogentembedded.com>"
# gpg:                 aka "Max Filippov <jcmvbkbc@gmail.com>"
# Primary key fingerprint: 2B67 854B 98E5 327D CDEB  17D8 51F9 CC91 F83F A044

* remotes/xtensa/tags/20180918-xtensa:
  target/xtensa: support input from chardev console
  target/xtensa: fix s32c1i TCGMemOp flags
  tests/tcg/xtensa: only generate defined exception handlers
  tests/tcg/xtensa: move exception handlers to separate section
  target/xtensa: fix FPU2000 bugs
  tests/tcg/xtensa: add test for failed memory transactions
  target/xtensa: convert to do_transaction_failed
  target/xtensa: add test_kc705_be core
  target/xtensa: clean up gdbstub register handling
  target/xtensa: fix gdbstub register counts

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