Add IObservableVector<T> stock implementation to windows-collections (#4324)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kennykerr <9845234+kennykerr@users.noreply.github.com>
Co-authored-by: Kenny Kerr <kenny@kennykerr.ca>

Author: Copilot

crates/libs/bindgen/src/types/delegate.rs

@@ -136,10 +136,12 @@ impl Delegate {
                             *iid == <windows_core::IUnknown as windows_core::Interface>::IID ||
                             *iid == <windows_core::imp::IAgileObject as windows_core::Interface>::IID {
                                 &mut (*this).vtable as *mut _ as _
-                            } else if *iid == <windows_core::imp::IMarshal as windows_core::Interface>::IID {
-                                (*this).count.add_ref();
-                                return windows_core::imp::marshaler(core::mem::transmute(&mut (*this).vtable as *mut _ as *mut core::ffi::c_void), interface);
                             } else {
+                                #[cfg(windows)]
+                                if *iid == <windows_core::imp::IMarshal as windows_core::Interface>::IID {
+                                    (*this).count.add_ref();
+                                    return windows_core::imp::marshaler(core::mem::transmute(&mut (*this).vtable as *mut _ as *mut core::ffi::c_void), interface);
+                                }
                                 core::ptr::null_mut()
                             };