jline integrated in the kulla repositories

[Jan Lahoda]

Hi,

jline 2.12.1 is now part of the kulla repositories. So when building 
full JDK, no additional parameters to make are needed, and the jshell 
command should work.

Regarding the scripts in langtools/repl/scripts, as jline is repackaged 
to jdk.internal.jline, the official jline.jar cannot be used anymore. 
I've updated the scripts so that they still should be usable on 
non-Windows platforms:
-if there is an up-to-date kulla's "jdk" repository checkout as a 
sibling to "langtools" repository (i.e. in the standard JDK layout), the 
scripts should automatically find it and use jline from the "jdk" 
repository.
-otherwise, please set "JDK_REPO_ROOT" property pointing to an 
up-to-date checkout of kulla's "jdk" repository.

Unfortunately, this won't work on Windows, as a little bit of native 
code is needed there. Please let me know if it is important to have 
these scripts work also for Windows.

Thanks,
    Jan