xamarin-macios/tests/mono-native/extra-linker-defs-watchos.xml

<?xml version="1.0" encoding="UTF-8" ?>
<linker>
        <assembly fullname="mscorlib">
                <type fullname="Mono.MonoNativePlatform" preserve="all" />
                <type fullname="Mono.MonoNativePlatformType" preserve="all" />
        </assembly>
</linker>