re PR tree-optimization/84982 (logically inverting bools into local array results in bitwise negation)

	PR tree-optimization/84982
	* gimple-ssa-store-merging.c (invert_op): Handle boolean inversion
	by flipping the least significant bit rather than all bits from
	bitpos to bitpos + bitsize - 1.

	* c-c++-common/pr84982.c: New test.

From-SVN: r258742