JDK-8029868 was backported to jdk7u as part of backporting July 2015 CPU. Class NSEvent was moved from package sun.lwawt.macosx.event to sun.lwawt.macosx package. But package name wasn't updated in make/sun/lwawt/FILES_export_macosx.gmk makefile, that causes build fail on Mac OS X.

Mailist thread with a fix: http://mail.openjdk.java.net/pipermail/jdk7u-dev/2015-August/010396.html