RFR(M) 8173846: [AOT] Stubs hang onto intermediate compiler state forever

[Igor Veresov]

This a port of Graal change that alters the API that is used by the jaotc. In order to maintain drop-in compatibility with Graal, it's important to follow this API change in jaotc. The change essentially gets rid of Stub.compResult and Stub.compiledCode fields that hang on to the compilation state.

Webrev: http://cr.openjdk.java.net/~never/aot-stub-changes/webrev

Thanks,
igor