Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

* Fix off-by-one in MODE SELECT commands
* extend --extra-*flags behavior to meson-based tests
* allow using snappy in static builds
* i386 TCG fixes
* fix build failure when libgbm is not available

# gpg: Signature made Mon 08 Nov 2021 12:20:24 PM CET
# gpg:                using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg:                issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>" [full]

* remotes/bonzini/tags/for-upstream:
  ui/gtk-egl: Fix build failure when libgbm is not available
  configure: ignore preexisting QEMU_*FLAGS envvars
  configure: propagate --extra-cflags and --extra-ldflags to meson compile tests
  configure: preserve CFLAGS, CXXFLAGS and LDFLAGS in config.status
  configure: simplify calls to meson_quote
  docs: adjust for demise of scripts/create_config
  meson: perform snappy test with the C++ compiler if used
  hw/scsi/scsi-disk: MODE_PAGE_ALLS not allowed in MODE SELECT commands
  target-i386: mmu: fix handling of noncanonical virtual addresses
  target-i386: mmu: use pg_mode instead of HF_LMA_MASK

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

diff --cc docs/devel/build-system.rst
Simple merge