Merge fix for JDK-6900441 from Linux source.

http://bugs.java.com/view_bug.do?bug_id=6900441

While we are at it, merge fix for JDK-8029453.

http://bugs.java.com/view_bug.do?bug_id=8029453

Note JDK-8029453 only affects us when "-XX:WorkAroundNPTLTimedWaitHang=0" is
forcibly set.

Reported by: 张泽鹏 (redraiment at gmail dot com)
Tested by: 张泽鹏 (redraiment at gmail dot com)