hg: jdk/sandbox: Enable volatileimage usage for back buffer

[jayathirth.d.v at oracle.com]

Changeset: 28582d575a98
Author:    jdv
Date:      2019-06-21 12:42 +0530
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/28582d575a98

Enable volatileimage usage for back buffer

! src/java.desktop/macosx/native/libawt_lwawt/awt/AWTSurfaceLayers.m
! src/java.desktop/macosx/native/libawt_lwawt/awt/AWTView.m
! src/java.desktop/share/classes/javax/swing/RepaintManager.java