Merge remote-tracking branch 'remotes/xtensa/tags/20190228-xtensa' into staging

target/xtensa: FLIX support, various fixes and test improvements

- add FLIX (flexible length instructions extension) support;
- make testsuite runnable on wider range of xtensa cores;
- add floating point opcode tests;
- don't add duplicate 'static' in import_core.sh script;
- fix undefined opcodes detection in test_mmuhifi_c3 overlay.

# gpg: Signature made Thu 28 Feb 2019 12:53:23 GMT
# gpg:                using RSA key 2B67854B98E5327DCDEB17D851F9CC91F83FA044
# gpg:                issuer "jcmvbkbc@gmail.com"
# gpg: Good signature from "Max Filippov <filippov@cadence.com>" [unknown]
# gpg:                 aka "Max Filippov <max.filippov@cogentembedded.com>" [full]
# gpg:                 aka "Max Filippov <jcmvbkbc@gmail.com>" [full]
# Primary key fingerprint: 2B67 854B 98E5 327D CDEB  17D8 51F9 CC91 F83F A044

* remotes/xtensa/tags/20190228-xtensa: (40 commits)
  tests/tcg/xtensa: add FPU2000 coprocessor tests
  tests/tcg/xtensa: add FP1 group tests
  tests/tcg/xtensa: add FP0 group conversion tests
  tests/tcg/xtensa: add FP0 group arithmetic tests
  tests/tcg/xtensa: add LSCI/LSCX group tests
  tests/tcg/xtensa: add test for FLIX
  tests/tcg/xtensa: conditionalize MMU-related tests
  tests/tcg/xtensa: conditionalize windowed register tests
  tests/tcg/xtensa: conditionalize and fix s32c1i tests
  tests/tcg/xtensa: fix SR tests for big endian configs
  tests/tcg/xtensa: conditionalize and expand SR tests
  tests/tcg/xtensa: conditionalize timer/CCOUNT tests
  tests/tcg/xtensa: conditionalize interrupt tests
  tests/tcg/xtensa: add straightforward conditionals
  tests/tcg/xtensa: conditionalize cache option tests
  tests/tcg/xtensa: conditionalize debug option tests
  tests/tcg/xtensa: enable boolean tests
  tests/tcg/xtensa: fix endianness issues in test_b
  tests/tcg/xtensa: don't use optional opcodes in generic code
  tests/tcg/xtensa: support configs with LITBASE
  ...

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