Merge tag 'pull-9p-20221024' of https://github.com/cschoenebeck/qemu into staging

9pfs: performance, Windows host prep, tests restructure

* Highlight of this PR is Linus Heckemann's GHashTable patch which
  brings massive general performance improvements of 9p server
  somewhere between factor 6 .. 12.

* Bin Meng's g_mkdir patch is a preparatory patch for upcoming
  Windows host support of 9p server.

* The rest of the patches in this PR are 9p test code restructuring
  and refactoring changes to improve readability and to ease
  maintenance of 9p test code on the long-term.

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# gpg: Good signature from "Christian Schoenebeck <qemu_oss@crudebyte.com>" [unknown]
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* tag 'pull-9p-20221024' of https://github.com/cschoenebeck/qemu: (23 commits)
  tests/9p: remove unnecessary g_strdup() calls
  tests/9p: merge v9fs_tunlinkat() and do_unlinkat()
  tests/9p: merge v9fs_tlink() and do_hardlink()
  tests/9p: merge v9fs_tsymlink() and do_symlink()
  tests/9p: merge v9fs_tlcreate() and do_lcreate()
  tests/9p: merge v9fs_tmkdir() and do_mkdir()
  tests/9p: convert v9fs_tflush() to declarative arguments
  tests/9p: simplify callers of twrite()
  tests/9p: convert v9fs_twrite() to declarative arguments
  tests/9p: simplify callers of tlopen()
  tests/9p: convert v9fs_tlopen() to declarative arguments
  tests/9p: simplify callers of treaddir()
  tests/9p: convert v9fs_treaddir() to declarative arguments
  tests/9p: simplify callers of tgetattr()
  tests/9p: convert v9fs_tgetattr() to declarative arguments
  tests/9p: simplify callers of tattach()
  tests/9p: merge v9fs_tattach(), do_attach(), do_attach_rqid()
  tests/9p: merge v9fs_tversion() and do_version()
  tests/9p: simplify callers of twalk()
  tests/9p: merge *walk*() functions
  ...

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>