sccvn: Punt on ref->size not multiple of 8 for memset (, 123, ) in 9.x [PR93945]

sccvn: Punt on ref->size not multiple of 8 for memset (, 123, ) in 9.x [PR93945]

And here is the corresponding 9.x change where we the patch just punts if
ref->size is not whole bytes, like we already punt if offseti is not byte
aligned.

2020-02-27  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/93945
	* tree-ssa-sccvn.c (vn_reference_lookup_3): For memset with non-zero
	second operand, require ref->size to be a multiple of BITS_PER_UNIT.

	* gcc.c-torture/execute/pr93945.c: New test.