* eval.c (evaluate_subexp_standard): Fix type of result of mixed

	* eval.c (evaluate_subexp_standard): Fix type of result of mixed
	integer/float division operations when EVAL_AVOID_SIDE_EFFECTS.
	* valops.c (value_one): New function.
	* value.h (value_one): Declare.

	Fix argument promotion for binary arithmetic ops for C.
	* valarith.c (unop_result_type): New fn.
	(binop_result_type): New fn.
	(value_binop): Move result type computation to binop_result_type.
	(value_pos, value_neg, value_complement): Move result type
	computation to unop_result_type.

	* gdb.base/whatis-exp.exp: Fix expected result of whatis x+y, x-y, x*y.