Review Request: JDK-8168205: Should not default class path to CWD if -cp is not specified but -m is specified

[Mandy Chung]

Webrev:
   http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8168205/webrev.00/index.html

If -cp is not specified and -m is not specified, the builtin system
class loader will default the class path to the current working 
directory.  If -m is specified, no -cp and CLASSPATH environment 
variable is not set, it should mean no class path.  This patch fixes
the case if -m is specified and the value of java.class.path is empty,
e.g. via -Djava.class.path option, then no class path should be set.

This patch also updates the launcher code used for generating launcher
for JDK tools. As the JDK tool no longer passes any class path, it
removes APP_CLASSPATH macro.

Mandy