Avoid redundant GORI calcuations.

Avoid redundant GORI calcuations.

When GORI evaluates a statement, if operand 1 and 2 are both in the
dependency chain, GORI evaluates the name through both operands sequentially
and combines the results.

If either operand is in the dependency chain of the other, this
evaluation will do the same work twice, for questionable gain.
Instead, simple evaluate only the operand which depends on the other
and keep the evaluation linear in time.

	* gimple-range-gori.cc (compute_operand1_and_operand2_range):
	Check for interdependence between operands 1 and 2.