JNI global references leak when native method registration fails

Summary

Java_com_sun_jna_Native_registerMethod creates persistent JNI references before several fallible FFI initialization steps.

Affected code: https://github.com/java-native-access/jna/blob/d036ad9781adad4b66693e8fa7098e4ac665e0a3/native/dispatch.c#L3553-L3587

If ffi_prep_cif, ffi_closure_alloc, or ffi_prep_closure_loc fails, execution jumps to cleanup. That path frees data without calling DeleteGlobalRef for data->closure_method.

Because registration did not complete, Native_unregister cannot release this reference later.

Impact

Each failed registration permanently retains the reflected Java Method and potentially its class-loader object graph until JVM shutdown. Repeated failures may cause persistent memory growth.

The same cleanup path also omits some related resources, including weak global references, closure_arg_types, encoding, and an allocated FFI closure.

Suggested fix

Before freeing data on failure:

• Delete closure_method with DeleteGlobalRef.
• Delete any from_native and to_native weak global references.
• Free all allocated arrays, encoding data, and FFI closure memory.

Successful registrations should continue to transfer ownership to Native_unregister.