Summary: Introduce alignment-safe Copy::conjoint_swap and JVM_CopySwapMemory
Reviewed-by: mikael, dholmes

Reviewed-by: prr

Reviewed-by: erikj

Summary: Correction of failed backport of JDK-8211394 via JDK-8212696.
Reviewed-by: dholmes, coffeys

Reviewed-by: neliasso, kvn

Reviewed-by: kvn

Reviewed-by: dholmes, jcbeyler

Reviewed-by: dbuck

Summary: Backport from JDK12
Reviewed-by: dholmes