configure: bump Meson to 1.9.0 for use with Rust

Meson 1.9.0 provides mixed linking of Rust and C objects.  As a side effect,
this also allows adding dependencies with "sources: ..." files to Rust crates
that use structured_sources().

It can also clean up up the meson.build files for Rust noticeably, but due
to an issue with doctests (see https://github.com/mesonbuild/meson/pull/14973)
that will have to wait for 1.9.1.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250908105005.2119297-3-pbonzini@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

xemu: Update minimum Meson requirement to 1.8.4 to facilitate building on
macOS with Clang 17.
Fixes #2442

configure

@@ -1194,6 +1194,16 @@ fi
 ##########################################
 # detect rust triple
 
+meson_version=$($meson --version)
+if test "$rust" != disabled && ! version_ge "$meson_version" 1.9.0; then
+  if test "$rust" = enabled; then
+    $mkvenv ensuregroup --dir "${source_path}/python/wheels" \
+         ${source_path}/pythondeps.toml meson-rust || exit 1
+  else
+    echo "Rust needs Meson 1.9.0, disabling" 2>&1
+    rust=disabled
+  fi
+fi
 if test "$rust" != disabled && has "$rustc" && $rustc -vV > "${TMPDIR1}/${TMPB}.out"; then
   rust_host_triple=$(sed -n 's/^host: //p' "${TMPDIR1}/${TMPB}.out")
 else