Merge remote-tracking branch 'remotes/stsquad/tags/pull-testing-docs-xen-updates...

Merge remote-tracking branch 'remotes/stsquad/tags/pull-testing-docs-xen-updates-100321-2' into staging

Testing, guest-loader and other misc tweaks

  - add warning text to quickstart example
  - add CFI tests to CI
  - use --arch-only for docker pre-requisites
  - fix .editorconfig for emacs
  - add guest-loader for Xen-like hypervisor testing
  - move generic-loader docs into manual proper
  - move semihosting out of hw/

# gpg: Signature made Wed 10 Mar 2021 15:35:31 GMT
# gpg:                using RSA key 6685AE99E75167BCAFC8DF35FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>" [full]
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8  DF35 FBD0 DB09 5A9E 2A44

* remotes/stsquad/tags/pull-testing-docs-xen-updates-100321-2:
  semihosting: Move hw/semihosting/ -> semihosting/
  semihosting: Move include/hw/semihosting/ -> include/semihosting/
  tests/avocado: add boot_xen tests
  docs: add some documentation for the guest-loader
  docs: move generic-loader documentation into the main manual
  hw/core: implement a guest-loader to support static hypervisor guests
  device_tree: add qemu_fdt_setprop_string_array helper
  hw/riscv: migrate fdt field to generic MachineState
  hw/board: promote fdt from ARM VirtMachineState to MachineState
  .editorconfig: update the automatic mode setting for Emacs
  tests/docker: Use --arch-only when building Debian cross image
  gitlab-ci.yml: Add jobs to test CFI flags
  gitlab-ci.yml: Allow custom # of parallel linkers
  tests/docker: add a test-tcg for building then running check-tcg
  docs/system: add a gentle prompt for the complexity to come

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