Only require the `supported` feature for non-extern-C functions.

PiperOrigin-RevId: 655948484
Change-Id: I09952c1edf53e7b68a8a5810306774bbf6fb5616

rs_bindings_from_cc/generate_bindings/lib.rs

diff --git a/rs_bindings_from_cc/generate_bindings/lib.rs b/rs_bindings_from_cc/generate_bindings/lib.rs
index feaeafc..03fc4be 100644
--- a/rs_bindings_from_cc/generate_bindings/lib.rs
+++ b/rs_bindings_from_cc/generate_bindings/lib.rs
@@ -830,7 +830,7 @@
                 } else {
                     require_any_feature(
                         &mut missing_features,
-                        ir::CrubitFeature::NonExternCFunctions | ir::CrubitFeature::Experimental,
+                        ir::CrubitFeature::Supported.into(),
                         &|| "non-extern \"C\" function".into(),
                     );
                 }