Tweak tests to avoid fallout from MEM_REF changes on targets that don't
enable store merging but achieve the same effect by other means (DSE).

gcc/testsuite?ChangeLog:

	PR middle-end/90676
	* gcc.dg/tree-ssa/pr30375.c: Adjust and simplify expected test
	output some more.
	* gcc.dg/tree-ssa/slsr-27.c: Ditto.
	* gcc.dg/tree-ssa/slsr-28.c: Ditto.
	* gcc.dg/tree-ssa/slsr-29.c: Ditto.
	* gcc.dg/tree-ssa/ssa-dse-24.c: Ditto.

From-SVN: r272218