title: timedelta error with numpy.longdouble dtype
body: <p>I have times with dtype <code>numpy.longdouble</code> and when I'm trying to use that values with <code>timedelta</code> function I've got errors. But when I convert it to <code>numpy.float64</code> everything is fine. Could somebody explain that behaviour?</p>
  
  <pre><code>import numpy as np
  from datetime import timedelta
  t1 = np.array([1000], dtype=np.longdouble)
  t2 = np.array([1000], dtype=np.float64)
  
  In [166]: timedelta(seconds=t1[0])
  TypeError: unsupported type for timedelta seconds component: numpy.float64
  
  In [167]: timedelta(seconds=t2[0])
  Out[167]: datetime.timedelta(0, 1000)
  
  In [168]: timedelta(seconds=t1[0].astype(np.float64))
  Out[168]: datetime.timedelta(0, 1000)
  </code></pre>
  
  <p>When I'm trying to see dtypes of variables they are look the similar but not the same:</p>
  
  <pre><code>In [172]: t1[0].dtype
  Out[172]: dtype('float64')
  
  In [173]: t2[0].dtype
  Out[173]: dtype('float64')
  
  In [174]: np.longdouble == np.float64
  Out[174]: False
  
  In [175]: t1[0].dtype == t2[0].dtype
  Out[175]: True
  </code></pre>
  
  <h1>Edit</h1>
  
  <p>And it's strange that it's not working for np.int32 and np.int64 either:</p>
  
  <pre><code>t3 = np.array([1000], dtype=np.int32)
  t4 = np.array([1000], dtype=np.int64)
  
  In [29]: timedelta(t3[0])
  TypeError: unsupported type for timedelta days component: numpy.int32
  
  In [69]: timedelta(t4[0])
  TypeError: unsupported type for timedelta days component: numpy.int64
  </code></pre>