BUG: loffset has no effect when passing in a numpy.timedelta64
- [x] closes #7687
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

restarted the failed travis worker. Could you add a release not in 0.24.0.txt? # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22482?src=pr&el=h1) Report
> Merging [#22482](https://codecov.io/gh/pandas-dev/pandas/pull/22482?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/db970894860fdf0a05056e43fc557ac995a2c6a0?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/22482/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/22482?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #22482      +/-   ##
==========================================
+ Coverage   92.04%   92.04%   +<.01%     
==========================================
  Files         169      169              
  Lines       50787    50787              
==========================================
+ Hits        46745    46746       +1     
+ Misses       4042     4041       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.45% <ø> (ø)` | :arrow_up: |
| #single | `42.29% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/22482?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/resample.py](https://codecov.io/gh/pandas-dev/pandas/pull/22482/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzYW1wbGUucHk=) | `96.13% <ø> (ø)` | :arrow_up: |
| [pandas/util/\_depr\_module.py](https://codecov.io/gh/pandas-dev/pandas/pull/22482/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX2RlcHJfbW9kdWxlLnB5) | `67.44% <0%> (+2.32%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22482?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/22482?src=pr&el=footer). Last update [db97089...4db1e81](https://codecov.io/gh/pandas-dev/pandas/pull/22482?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @discort 