testsuite, Darwin: In tsvc.h, use malloc for Darwin <= 9.

Earlier Darwin versions fdo not have posix_memalign() but the
malloc implementation is guaranteed to produce memory suitably
aligned for the largest vector type.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/tsvc/tsvc.h: Use malloc for Darwin 9 and
	earlier.