re PR tree-optimization/83337 (ICE at -O3 x86_64-linux-gnu: in interpret_rhs_expr, at tree-scalar-evolution.c:1775)

	PR tree-optimization/83337
	* gimple-loop-interchange.cc (compute_access_stride): Handle bitfield DRs
	properly.

	* gcc.dg/tree-ssa/loop-interchange-14.c: New test.
	* gcc.dg/tree-ssa/loop-interchange-15.c: New test.

From-SVN: r255528