DataFrame: Ctor from non abc.Iterable 2-d array like
In case we pass a 2d array like that do not use __iter__ but the
__getitem__ interface, it falls outside the collection.abc.Iterable case
and throw.

- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @jschueller! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-02-20 07:32:56 UTC can you run `black pandas/tests/frame/test_constructors.py` what use case is likely to lead to this kind of input? Maybe a lack of understanding but not sure I see this as being useful and worth supporting. Does this reference an open issue? we have a container that behaves like this in openturns:
http://openturns.github.io/openturns/master/user_manual/_generated/openturns.Sample.html?highlight=sample#openturns.Sample

this change would allow to use the DataFrame ctor directly:
```
import openturns as ot
import pandas as pd
sample = ot.Normal(3).getSample(10)
df = pd.DataFrame(data=sample, columns=sample.getDescription())
```

for now we can only build a DataFrame using from_records:
```
df = pd.DataFrame.from_records(sample, columns=sample.getDescription())
```

One could consider inconsistent that it succeeds with from_records and not with the ctor


 It's not that it is not iterable, it's just that it does not use the __iter__/__next__ interface for iteration but the __gettitem__ interface, and so it's not getting in the abc.Iterable case of the DataFrame ctor In a vacuum this is OK, but my main concern is that we don’t comprehensively support this type of “iterable” so somewhat weird to do one-off here. Not sure it would even be worth the effort for other pandas objects that we construct from iterables, so I think I would be -1 on moving forward with this [sadface] Thanks in any case @jschueller - we disagree on this one but attempt is in any case appreciated. Certainly would welcome more in the future