BUILD: build issues on windows
so from latest master w latest deps
- [x] closed by #13736

```
======================================================================
ERROR: test_nanosecond_field (pandas.tseries.tests.test_timeseries.TestDatetime64)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\dev\pandas\pandas\tseries\tests\test_timeseries.py", line 3925, in test_nanosecond_field
    dti = DatetimeIndex(np.arange(10))
  File "C:\dev\pandas\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
  File "C:\dev\pandas\pandas\tseries\index.py", line 337, in __new__
    if isinstance(subarr, DatetimeIndex):
UnboundLocalError: local variable 'subarr' referenced before assignment
```
- [x] closed by #13732 

```
======================================================================
FAIL: test_next (pandas.io.tests.test_common.TestMMapWrapper)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\dev\pandas\pandas\io\tests\test_common.py", line 141, in test_next
    self.assertEqual(next_line, line)
AssertionError: 'a,b,c\r\n' != 'a,b,c\n'
- a,b,c
?      -
+ a,b,c

```

I think some @sinhrks changes for the first
not sure about the 2nd, IIRC @pijucha saw this on windows as well

@gfyoung any idea?d
