gfortran.dg/vect failures at -m64 on darwin fix

[Jack Howarth]

   For folks on the Darwin ppc platform that have been following
this thread, Dorit Nuzman has crafted some changes to the gcc and
gfortran vect testsuites which eliminates the false failures on
powerpc-apple-darwin8/9 at -m64. These changes eliminated 18 failures
from the gcc.dg testsuite at -m64 and all of the vect related failures
in the gfortran.dg testsuite at -m64. Hopefully we will be able to
get those changes into gcc trunk soon as it does dramatically reduce
the noise on the -m64 testsuite results for powerpc-apple-darwin.
                 Jack