Changes contributed by Manfred under https://github.com/eclipse/org.aspectj/pull/5/commits

This commit introduces some new methods into the
runtime Factory class and modifies code generation
to use them (and to use the form of the LDC bytecode
that loads class constants).

Prior to this AspectJ would discard ignore the ClasspathEntry
objects built by JDT and just work with the classpath as a string,
driving the JDT FileSystem to rebuild classpath entries again at
a later date using the string. This is more complex in Java9 because
the string representation was losing whether some entries came in
via modulepath.  ClasspathEntry construction for modulepath entries
is non trivial (since the module-info must be processed).

The new version will cache some of the ClasspathEntry objects (those
built for modulepaths) and do more work on the AspectJ side building
classpath entries in general. It now passes these entries to a
different FileSystem entry point rather than the entry point that
takes a string path.

Some new code in JDT is using the information in here, so need
to resolve them.

clone is saying it is protected rather than public and so we need
to add a guard to avoid creating accessor for it.

If an anonymous class calls a method ITD'd onto one of its own
supertypes (e.g. new A() { xx(null); }) then it can be reported
as an ambiguous method invocation on Java8. There is different
handling for Java8 that is revealing an issue. The intertype
method declarations are recorded in a member finder attached to the
target type (A in this case). When the local type binding is
built it gets all the methods from supertypes added to it - this
unfortunately includes the ITD method.  Then later when something
asks for all 'xx' methods on A, it finds the ITD method from when
A was constructed and an additional copy from the member finder.

The quick fix is for the member finder to use a set rather than
list when answering 'what are the xx methods'. If this proves
a problem down the line the deeper fix would be to avoid including
ITDs when the local type binding is built.