Merge tag 'staging-pull-request' of https://gitlab.com/peterx/qemu into staging

Migration pull for rc2

- Zhijian's COLO regression fix (since 10.0)
- Matthew's fix to avoid crash on wrong list manipulations
- Markus's error report leak fix and cleanups
- Peter's qtest changes to merge memory_backend and use_shmem

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* tag 'staging-pull-request' of https://gitlab.com/peterx/qemu:
  tests/migration-test: Use MEM_TYPE_MEMFD for memory_backend
  tests/migration-test: Add MEM_TYPE_SHMEM
  tests/migration-test: Merge shmem_opts into memory_backend
  tests/migration-test: Introduce MemType
  migration/postcopy-ram: Improve error reporting after loadvm failure
  migration: Use warn_reportf_err() where appropriate
  migration: Plug memory leaks after migrate_set_error()
  migration: set correct list pointer when removing notifier
  migration: Fix transition to COLO state from precopy

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