Merge remote-tracking branch 'remotes/stsquad/tags/pull-for-6.2-121021-2' into staging

Merge remote-tracking branch 'remotes/stsquad/tags/pull-for-6.2-121021-2' into staging

Some testing and plugin updates:

  - don't override the test compiler when specified
  - split some multiarch tests by guest OS
  - add riscv64 docker image and cross-compile tests
  - drop release tarball test from Travis
  - skip check-patch on master repo
  - fix passing of TEST_TARGETS to cirrus
  - fix missing symbols in plugins
  - ensure s390x insn start ops precede plugin instrumentation
  - refactor plugin instruction boundary detection
  - update github repo lockdown
  - add a debian-native test image for multi-arch builds

# gpg: Signature made Tue 12 Oct 2021 02:35:00 AM PDT
# gpg:                using RSA key 6685AE99E75167BCAFC8DF35FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>" [full]

* remotes/stsquad/tags/pull-for-6.2-121021-2:
  tests/docker: add a debian-native image and make available
  .github: move repo lockdown to the v2 configuration
  accel/tcg: re-factor plugin_inject_cb so we can assert insn_idx is valid
  target/s390x: move tcg_gen_insn_start to s390x_tr_insn_start
  plugins/: Add missing functions to symbol list
  gitlab: fix passing of TEST_TARGETS env to cirrus
  gitlab: skip the check-patch job on the upstream repo
  travis.yml: Remove the "Release tarball" job
  gitlab: Add cross-riscv64-system, cross-riscv64-user
  tests/docker: promote debian-riscv64-cross to a full image
  tests/tcg: move some multiarch files and make conditional
  tests/tcg/sha1: remove endian include
  configure: don't override the selected host test compiler if defined

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>