TST: DataFrame.hist() does not get along with matplotlib.pyplot.tight_layout()
 - [ ] closes #9351
 - [ ] tests added / passed
 - [ ] passes ``git diff upstream/master | flake8 --diff``
 - [ ] whatsnew entry

Note: in addition to the #9351 unit test this PR also adds a `_skip_if_mpl_1` method to the test utilities. I rewrote the test using `mpl_ge_2_0_0` and removed the aux method. `pytest` isn't a name in `test_hist_method`, and I don't see a generic skip in `testing.py`, so I've just made the test conditional, e.g. there's no explicit skip. Let me know if that's OK or not. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15515?src=pr&el=h1) Report
> Merging [#15515](https://codecov.io/gh/pandas-dev/pandas/pull/15515?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b3ae4c7698de4623e1279d579b46192ef79250d1?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.


```diff
@@            Coverage Diff             @@
##           master   #15515      +/-   ##
==========================================
+ Coverage   90.36%   90.36%   +<.01%     
==========================================
  Files         136      136              
  Lines       49553    49554       +1     
==========================================
+ Hits        44780    44781       +1     
  Misses       4773     4773
```


| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15515?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/compare/b3ae4c7698de4623e1279d579b46192ef79250d1...809d8473677bce11dd780ecb332b130c3b523c9a?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `96.31% <0%> (ø)` | :white_check_mark: |
| [pandas/types/cast.py](https://codecov.io/gh/pandas-dev/pandas/compare/b3ae4c7698de4623e1279d579b46192ef79250d1...809d8473677bce11dd780ecb332b130c3b523c9a?src=pr&el=tree#diff-cGFuZGFzL3R5cGVzL2Nhc3QucHk=) | `85.45% <0%> (+0.02%)` | :white_check_mark: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15515?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/15515?src=pr&el=footer). Last update [b3ae4c7...809d847](https://codecov.io/gh/pandas-dev/pandas/compare/b3ae4c7698de4623e1279d579b46192ef79250d1...809d8473677bce11dd780ecb332b130c3b523c9a?el=footer&src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments). lgtm. ping on green. actually, pls add a whatsnew note as well (I guess in Bug Fixes). This is really a mpl compat issue, and there isn't much we can do about it with < 2.0.0, so best just to note this in the whatsnew as well so readers can react to this. lgtm. thanks. thanks!