8183103: Post loop vectorization produces incorrect results
Summary: Disable AVX=3 and PostLoopMultiversioning by default and make them experimental in JDK 9.
Reviewed-by: kvn

8168503: JEP 297: Unified arm32/arm64 Port
Reviewed-by: kvn, enevill, ihse, dholmes, erikj, coleenp, cjplummer