Implement range-op dispatch for prange.

Implement range-op dispatch for prange.

This patch adds the range-op dispatch code for prange, and adds some
temporary sanity checks (for flag_checking only) to make sure we handle
all the pointer/integer variants.

In order to make sure I got all the combinations right, I started with
a clean slate, trapping on all pointer operands.  Then I added support
for each one piecemeal.  To verify the work, I added a
pointers_handled_p() helper that is implemented for each range-op
entry and returns TRUE iff the operator can handle a given combination
of pointers.  If this helper returns false, we will trap, because it
indicates an operator that was not implemented.  This is temporary
checking code, and I will rip it out once the the dust has
settled in a few days.

gcc/ChangeLog:

	* range-op-mixed.h: Add using declarator for all classes.
	* range-op-ptr.cc (range_operator::pointers_handled_p): New.
	(range_operator::fold_range): New.
	(range_operator::op1_op2_relation_effect): New.
	(range_operator::op1_range): New.
	(range_operator::op2_range): New.
	(range_operator::op1_op2_relation): New.
	(range_operator::lhs_op1_relation): New.
	(range_operator::update_bitmask): New.
	(class pointer_plus_operator): New.
	(class operator_pointer_diff): New.
	(class hybrid_min_operator): New.
	(class hybrid_max_operator): New.
	* range-op.cc: Add RO_PPP, RO_PPI, RO_IPP, RO_IPI, RO_PIP, RO_PII.
	(range_op_handler::discriminator_fail): New.
	(has_pointer_operand_p): New.
	(range_op_handler::fold_range): Add pointer support.
	(range_op_handler::op1_range): Same.
	(range_op_handler::op2_range): Same.
	(range_op_handler::lhs_op1_relation): Same.
	(range_op_handler::lhs_op2_relation): Same.
	(range_op_handler::op1_op2_relation): Same.
	(class operator_div): Add using.
	(class operator_lshift): Add using.
	(class operator_rshift):Add using.
	(class operator_trunc_mod):Add using.
	(class operator_absu):Add using.
	* range-op.h (enum range_op_dispatch_type): New.
	Add extern definitions for RO_*.