Optimizer [treeopt]: Support operator call short-hand.

A short-hand notation may now be used to match operator calls.
Eg the following fragment:

  F_APPLY(F_CONSTANT[TYPEOF($$->u.sval) == T_FUNCTION]
		    [SUBTYPEOF($$->u.sval) == FUNCTION_BUILTIN]
		    [$$->u.sval.u.efun->function == f_ge],
	  F_ARG_LIST(X, Y))

can now be written as:

  F_GE(X, Y)