BUG: Fix nansum overflow on Windows with bottleneck
Bottleneck used in nansum produces overflow error on Windows. Temporary fix that could be undone once the error in bottleneck is fixed and released, to avoid platform specificity.

 - [x] closes #15453 
 - [x] tests added / passed
 - [x] passes ``git diff upstream/master | flake8 --diff``
 - [x] whatsnew entry
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15507?src=pr&el=h1) Report
> Merging [#15507](https://codecov.io/gh/pandas-dev/pandas/pull/15507?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/23889d3ec8396925269210d6d5782574e61769bd?src=pr&el=desc) will **decrease** coverage by `-0.07%`.
> The diff coverage is `100%`.


```diff
@@            Coverage Diff             @@
##           master   #15507      +/-   ##
==========================================
- Coverage    91.1%   91.03%   -0.07%     
==========================================
  Files         136      136              
  Lines       49102    49103       +1     
==========================================
- Hits        44736    44703      -33     
- Misses       4366     4400      +34
```


| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15507?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/nanops.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvbmFub3BzLnB5) | `97.96% <100%> (-0.21%)` | :x: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `40% <0%> (-46.67%)` | :x: |
| [pandas/util/decorators.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvZGVjb3JhdG9ycy5weQ==) | `67.92% <0%> (-1.31%)` | :x: |
| [pandas/io/pytables.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2lvL3B5dGFibGVzLnB5) | `93.05% <0%> (-0.86%)` | :x: |
| [pandas/tools/merge.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL3Rvb2xzL21lcmdlLnB5) | `91.78% <0%> (-0.35%)` | :x: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.74% <0%> (-0.1%)` | :x: |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `94.93% <0%> (-0.04%)` | :x: |
| [pandas/core/algorithms.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYWxnb3JpdGhtcy5weQ==) | `94.48% <0%> (ø)` | :white_check_mark: |
| [pandas/compat/pickle_compat.py](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9waWNrbGVfY29tcGF0LnB5) | `68.29% <0%> (ø)` | :white_check_mark: |
| ... and [3 more](https://codecov.io/gh/pandas-dev/pandas/pull/15507?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15507?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15507?src=pr&el=footer). Last update [23889d3...7b95a88](https://codecov.io/gh/pandas-dev/pandas/compare/23889d3ec8396925269210d6d5782574e61769bd...7b95a881c6de9367cbe5afa4e23bdfa9c6c6360b?src=pr&el=footer&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments). @jorisvandenbossche @shoyer 

w.r.t. #9422 I think we need to simply change this (in effect what this PR does), but for all platforms (and not just windows).
 @JaviSorribes Looking at @jreback's comments, it looks like we should just disable `nansum` bottleneck calls altogether. So I understand @jreback and @cpcloud that we should not use bottleneck at all for nansum? Checkout the image attached for what I think this would look like.

Also, what about all the other nan operations? Should we consider possible overflow in any of them?

![image](https://cloud.githubusercontent.com/assets/15252789/23396198/3420769c-fd58-11e6-85bd-4c9001dd032d.png) xref #15542  We indeed just need to take a decision on #9422, as we have left this lingering too long. 
But, I am not necessarily convinced that we should change everything to the native pandas way (returning NaN), instead of changing pandas to return 0 to align with numpy/bottleneck (and also R, matlab, ..). 
I don't think there was really agreement on this in #9422 (several have argued for both positions), but I also don't know how to best proceed on taking a decision. The fixes are related to fixing #9422 are a bit bigger in scope than this. That said If you want to rebase / add some additional tests could take this as a precurser. closing this. as #9422 needs resolution.