Code cleanup to avoid tricky macros and old-style function declarations.

Code cleanup to avoid tricky macros and old-style function declarations.

(cmpf, less_than, less_equal, equal, not_equal, greater_equal,
greater_than, arithf, arithdivf, plus, minus, multiply, divide, mod):
Remove.

(eval4, eval3, eval2): Rewrite to avoid the need for the above macros
and functions.