Review Request for JDK-8003992: File and other classes in java.io do not handle embedded nulls properly

Hi All, Please help review the fix for JDK-8003992: File and other classes in java.io do not handle embedded nulls properly. Java IO, not like NIO, does not check NUL character in the given file path name, which brings confusion to Java users. This fix is going to address this issue by removing any NUL character from the given file path. And it also cleans and optimizes the path-name normalization logic. Thanks! Bug: https://jbs.oracle.com/bugs/browse/JDK-8003992 webrev: http://cr.openjdk.java.net/~dxu/8003992/webrev.00/ -Dan