pandas-ci pip test failling
https://travis-ci.org/pandas-dev/pandas-ci/jobs/411446775#L2809

failling with

```
                   from pandas/_libs/hashing.c:596:
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/core/include/numpy/npy_1_7_deprecated_api.h:15:2: warning: #warning "Using deprecated NumPy API, disable it by " "#defining NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION" [-Wcpp]
   #warning "Using deprecated NumPy API, disable it by " \
    ^
  pandas/_libs/hashing.c:610:35: fatal error: ../src/headers/stdint.h: No such file or directory
   #include "../src/headers/stdint.h"
                                     ^
  compilation terminated.
  error: command 'gcc' failed with exit status 1
  
  ----------------------------------------
  Failed building wheel for pandas
```

