Track initialized final field updates; disable constant folding if an update is detected. Enforce final field update rules introduced by JVMS-7 (but only for JDK 9). Reviewed-by: vlivanov, dnsimon, forax, never, kvn, coleenp
Reviewed-by: alanb, jfranck, mchung
Reviewed-by: twisti, dpochepk
Reviewed-by: ihse, alanb, roland, coleenp, iveresov, kvn, kbarrett
