fcvt.d.s tests only test non-NaN-boxed input values

[jakubadler]

In fcvt.d.s_b1-01.S (and all other fcvt.d.s tests), all the test data use 64 for the __width__ argument of NAN_BOXED even thought the argument is supposed to be float32. I assume it should be 32 in most cases. The way it is now, no NaN-boxing takes place and thus only the one case of the input operand not being correctly NaN-boxed is tested.