Fix an error in the recursive call in libffi-type-pointer for
foreign-struct-type, now parse the slot-type, which is unparsed.  This
makes FSBV.3 and FSBV.4 succeed.  Removed quote from test FSBV.2; this
makes FSBV.2 succeed.

* Instead of a special variable, the parsed struct type instance is now
  annotated to let the type system know whether we're dealing with
  deprecated semantics (struct type canonicalizes to :pointer) or not.

  This approach should hopefully be much less error-prone.

* Disabled translations for bare structs.

* Fixed and commented out some bogus tests.

This broke other stuff, so revert until we understand what's happening

This reverts commit 944d3318.

Improved the documentation for Foreign Structure Types to more clearly
describe the behavior of mem-aref under the new structure reference
syntax and the compatibility of the bare structure reference with the
old behavior.

Create a new function #'foreign-expand-runtime-translator-or-binding
which is what the methods
  expand-to-foreign-dyn (value var body (type enhanced-foreign-type))
  expand-to-foreign-dyn-indirect (value var body (type translatable-foreign-type))
both call.  Previously, the body of that function was the body of the
first method, and the second method called that generic function.
This did not work as intended however, the result being that libffi
calls were passed the actual object instead of the pointer.  This
change fixes that problem.

New function expand-to-foreign-dyn-indirect split out from
expand-to-foreign-dyn, and the latter function returned to its
definition as given in the tip of master, ab10be4f.  This function
is used if the optional argument 'indirect to translate-objects is T,
which in turn the case when functions are calling or return structures
by value.

Multi-level optimizations depending what arguments are constantp; 
the constantp arguments need to be evaled.

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

Comment referred to "FSBV" now corrected to "libffi".  Other uses (the
tests and foreign library for tests, the *feature* symbol, and the
variable 'fsbvp resulting from fn-call-by-value-p) genuinely refer to
FSBV and not specifically libffi.  Distinction: "FSBV" refers to all
calls of structures by value, whether accomplished with the help of
libffi or not (some compilers have FSBV built in), "libffi" refers to
the use of the libffi library whether or not for calling foreign
structures by value (there are other functions not yet made use of in
CFFI, but someday might).

Conflicts:
	tests/GNUmakefile

Patch courtesy of Mark Evenson.

Patch courtesy of Mark Evenson.

Patch courtesy of James Anderson.

New function mem-aptr will return the pointer to the requested element
of the array, and add documentation.  It is untested.

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.

Bug reported by Anton Vodonosov.