The return_ul.c test is failing for mips64 n32 ABI.  The problem is that 
the return value location was too small and was overflowing into 
adjacent memory.

According to the libffi README, return values must be at least as large 
as ffi_arg, so that is what I used.

Tested on x86_64-pc-linux-gnu and mips64-linux-gnu.

OK to commit?

2007-08-01  David Daney  <ddaney@avtrex.com>

    * testsuite/libffi.call/return_ul.c (main): Define return type as
    ffi_arg.  Use proper printf conversion specifier.