[testsuite] Enable vect_usad_char effective target for non-SVE aarch64

[testsuite] Enable vect_usad_char effective target for non-SVE aarch64

In GCC 9 the aarch64 port learned how to do V16QImode SAD operations on signed and unsigned chars.
But I had missed enabling the effective target for that.
This patch enables that target for non-SVE aarch64.
Two new tests now PASS on aarch64:
gcc.dg/vect/slp-reduc-sad.c
gcc.dg/vect/vect-reduc-sad.c

	* lib/target-supports.exp (check_effective_target_vect_usad_char):
	Add non-SVE aarch64 to supported list.

From-SVN: r267230