dfp.c (decimal_real_arithmetic): Change second argument type from int to enum tree_code.

dfp.c (decimal_real_arithmetic): Change second argument type from int to enum tree_code.

	* dfp.c (decimal_real_arithmetic): Change second argument type
	from int to enum tree_code. Do not always return true, but now
	return result of any call to decimal_do helper functions.
	* dfp.h (decimal_real_arithmetic): Update prototype.

From-SVN: r110626