cffi-libffi: libffi-win32 fix
Modify STRUCTURE-BY-VALUE-P and include test cases
Merge pull request #21 from crlf0710/master

More library names and fix :sizet typo for windows.  Expand affirmative return from structure-by-value-p to include typedefs, so that foreign function calls by value may use the typedefed names to declare variable.  Includes tests.