Bug 225504

Description of problem:
When rmic from gcj is used to compile a stub/skel, it sets the "interfaceHash"
field of the generated skel/stub to a pointer location. This means that each
time that a stub/skel is compiled, the interfaceHash value changes. However,
this behaviour has unexpected consequences.

The interfaceHash value is used in the generated skeleton's dispatch() method to
ensure that it matches the value provided by the stub. This is a problem because
if the stub was re-compiled (for whatever reason), the interfaceHash value will
not match even though there has been no code change. The proper way to compute
interfaceHash is to rely on the file url and the contents of the file, so that
they are unique for a given url/code combination, but same for all copilations.

Version-Release number of selected component (if applicable):
All versions

How reproducible:
Always

Steps to Reproduce:
1. Compile a set of stub/skel with rmic and check the value of interfaceHash
(either by keeping  generated source, or by using jcf-dump on the class)
2. Repeat step 1
3. Compare value of interfaceHashes from 1 and 2
  
Actual results:
The values are different

Expected results:
The values should be the same

Additional info:
To fix this, Mark Wielaard suggested the use of
ObjectStreamClass.lookup(clazz).getSerialVersionUID() to compute the
interfaceHash instead of using RMIHashes.getInterfaceHash() as is currently the
case.