Java.so used to correctly support the "-jar" option, but did not fully
allow the other "mode" of running Java: specifying a class name which is
supposed to be searched in the class path. The biggest problem was that
it only know to find class files, but not a class inside a jar in the class
path - even if the classpath was correctly set.

Unfortunately, fixing this C code was impossible, as JNI's FindClass()
simply doesn't know to look in Jars.

So this patch overhauls java.so: Java.so now only runs a fixed class,
/java/RunJava.class. This class, in turn, is the one that parses the
command line arguments, sets the class path, finds the jar or class to
run, etc.. The code is now much easier to understand, and actually works
as expected :-) It also fixes the bug we had with SpecJVM2008's "compiler.*"
benchmarks, which forced us to tweak the class path manually.

The new code supports running a class from the classpath, and also the
"-classpath" option to set the class path. Like the "java" command line
tool in Linux, this one also recognizes wildcard classpaths. For example,
to run Jetty, whose code is in a dozen jars in /jetty, one can do:

        run.py -e "java.so -classpath /jetty/* org.eclipse.jetty.xml.XmlConfiguration jetty.xml"