File ffcall/avcall/tests.output/mips-sgi-irix6.4-cc-n32-O.README artifact 6f9866ec85 part of check-in a7dfaea4be

On mips-sgi-irix6.4 with "cc -n32", avcall does not handle correctly
structure return values which consist of 1 or 2 floats or doubles.
(The return values are found in $f0 and $f2, but avcall expects them
in $2 and $3.)