meson: replace deprecated meson.get_cross_property(...) with meson.get_external_property(...)

According to the deprecation note:
> It's a pure subset of meson.get_external_property, and works strangely
> in host == build configurations, since it would be more accurately
> described as get_host_property.

Signed-off-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19904>

src/compiler/nir/meson.build

@@ -437,7 +437,7 @@ if with_tests
     ),
     suite : ['compiler', 'nir'],
     # TODO: Use a negative filter for gtest instead of the expect failure here.
-    should_fail : meson.get_cross_property('xfail', '').contains('load_store_vectorizer'),
+    should_fail : meson.get_external_property('xfail', '').contains('load_store_vectorizer'),
     protocol : gtest_test_protocol,
   )