RFR [XS] 8153297 - [TESTBUG] Enhance test/testlibrary/ClassFileInstaller.java to support JAR files

[Ioi Lam]

Please review a very small fix:

http://cr.openjdk.java.net/~iklam/jdk9/8153300-enhance-classfileinstaller.v01/

Bug: [TESTBUG] Enhance test/testlibrary/ClassFileInstaller.java to 
support JAR files

https://bugs.openjdk.java.net/browse/JDK-8153300

Summary of fix:

     Many hotspot tests need to create JAR files. The current method is 
messy:

     [1] Because JTREG compiles .class files into various directories, 
we need
         to use ClassFileInstaller to find the .class file and copy it 
into the
         current directory.
     [2] Then, there are various ad-hoc calls to sun.tools.jar.Main to 
create the
         JAR file. This is not desirable because sun.tools.jar is an 
internal
         package and javac gives warnings about it.

     I have improved ClassFileInstaller so that JAR files can be easily
     created using JTREG tags:

     * @build ClassFileInstaller sun.hotspot.WhiteBox
     * @run main ClassFileInstaller -jar whitebox.jar sun.hotspot.WhiteBox

     To handle more complex use cases, new APIs are also added to 
ClassFileInstaller
     for programmatically creating JAR files inside the test source code.

     I converted two CDS test cases to use the new functionality.

     FYI, I am also working on new tests for a closed issue 
(JDK-8153297) that use
the new functionality.

Thanks
- Ioi