hg: jdk/jdk: 8224042: Add private alignDown method to MappedByteBuffer

[adinn at redhat.com]

Changeset: c1143a0d4e22
Author:    adinn
Date:      2019-05-16 15:45 +0100
URL:       http://hg.openjdk.java.net/jdk/jdk/rev/c1143a0d4e22

8224042: Add private alignDown method to MappedByteBuffer
Summary: Use alignDown method to round addresses down to page boundary
Reviewed-by: stuefe, mikael, alanb

! src/java.base/share/classes/java/nio/MappedByteBuffer.java