This makes sure that the store a memset is folded to uses a type
covering all bits.

2020-03-18   Richard Biener  <rguenther@suse.de>

	PR middle-end/94206
	* gimple-fold.c (gimple_fold_builtin_memset): Avoid using
	partial int modes or not mode-precision integer types for
	the store.

	* gcc.dg/torture/pr94206.c: New testcase.