Ubuntu 11.10 ships with libffi6 and not libff5, so these libraries are
now added to the load list.

Use hash table for libffi-type-pointer instead of a class slot, and
simplify #'libffi-type-pointer methods.  Remove obsolete package
definition file.  Tests in cffi-tests not run due to error in load,
but GSLL tests pass.

Use soname with major version for libffi on unix as advocated on 
http://lispcaveats.tumblr.com/post/13259176455/ffi-linking-against-shared-libraries.

Tests fsbv.1 and fsbv.2 added that test foreign structure call and
return by value.  This includes the C file and addition to makefile to
generate the appropriate library, libfsbv.  So that the tests are
properly defined, load cffi-fsbv and then cffi-tests.  Both tests
should pass.  The test returning a structure, fsbv.2, exposed an error
in the form generated by ffcall-body-libffi; because it always
generated a mem-aref on the return value, the subsequent
translate-from-foreign was effectively making a double translation.
Thus, this form generation has been conditionalized so that if
translate-from-foreign will not be applied (e.g., built-in-type) to
call mem-aref, otherwise just return the pointer.

Generic function translate-into-foreign-memory and funtion
convert-into-foreign-memory definitions now loaded by cffi.  System
cffi-fsbv defined for calling functions with foreign structures by
value using libffi.  Current state of this system is to make
libffi-type-pointer and associate with the structure in defcstruct.
This works on test structure
(macroexpand '(defcstruct (complex :class complex-type) (real :double) (imag :double)))
but nothing further is done with the libffi-type-pointer.

To do: fix lookup-type so that if there is no type defined, it returns
nil.  Do iterate-foreign-structure in advance of macro expansion in
cstruct-libffi-hook, if any arguments lack type translation, then
return nil.  This means that that structure can not be passed/returned
by value.  Then load cif after cstruct.  Secondary bug fix: defsynonym
'unsigned to something, not sure what it's supposed to be; :uint?