BUG: pd.array(floatdata, dtype=np.inty) should use astype_nansafe
```
In [8]: arr = np.random.randn(2)

In [9]: arr[0] = np.nan

In [10]: pd.array(arr, dtype="i8")
Out[10]: 
<PandasArray>
[-9223372036854775808, 1]
Length: 2, dtype: int64
```

Our other constructors all refuse to cast nan to a nonsense int