Review request for 6926663: incremental modules build support

[Mandy Chung]

Alan, Kelly,

Webrev:
    http://cr.openjdk.java.net/~mchung/6926663

It in fact contains 2 fixes:
1. integrate the latest jdk modularity fixes from jigsaw repos
    - add modules target in the top forest makefile [1]
    - support SKIP_BOOT_CYCLE=false modules build [2]
    - fix a couple of bugs in the launcher [3]
    - add JDK_HOST_PATH to support cross-architectural modules build [4]
    - cleanup on the modules.config and module names in makefiles

2.  incremental modules build support to ease jdk development
    - the changes are mainly in make/modules and 
make/tools/classanalyzer files.

    The modules build includes two main steps:
    a. run the class analyzer tool to assign classes and resources in 
the jdk modules and analyzes their dependencies
    b. modularize the build output and create a module library 
containing the jdk modules

I created a new tool com.sun.classanalyzer.Modularizer to do the files 
copying in step 2.  Both ClassAnalyzer and Modularizer will process 
classes/resources files that are updated since the previous build.  The 
jdk build will update a new file submodules/.modules.update if classes 
are recompiled, a library is rebuilt, or a file is installed in the jdk. 
  The modules build will use the timestamp of .modules.update file to 
determine if it should do an incremental or do a full modules build.

Thanks
Mandy

[1] http://mail.openjdk.java.net/pipermail/jigsaw-dev/2010-March/000742.html
[2] http://mail.openjdk.java.net/pipermail/jigsaw-dev/2010-March/000613.html
[3] 
http://mail.openjdk.java.net/pipermail/jigsaw-dev/2010-February/000523.html
[4] http://mail.openjdk.java.net/pipermail/jigsaw-dev/2010-March/000683.html