Introduce binop_operation

Introduce binop_operation

This adds two new template classes, binop_operation and
usual_ax_binop_operation, and then uses these to implement a number of
binary operations that follow similar patterns.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* expop.h (class binop_operation, class usual_ax_binop_operation):
	New.
	(exp_operation, intdiv_operation, mod_operation, mul_operation)
	(div_operation, rem_operation, lsh_operation, rsh_operation)
	(bitwise_and_operation, bitwise_ior_operation)
	(bitwise_xor_operation): New typedefs.
	* eval.c (eval_op_binary): No longer static.