Is libtool a requirement?

* Populus Version: 1.11.2 (but probably exists on 2.x as well?)
* OS: linux

### What was wrong?

Installing populus via pip fails:

```
File "/tmp/pip-build-y1mkwiga/secp256k1/setup.py", line 165, in run
cwd=absolute("libsecp256k1"),
File "/usr/lib/python3.6/subprocess.py", line 291, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['/tmp/pip-build-y1mkwiga/secp256k1/libsecp256k1/autogen.sh']' returned non-zero exit status 1.
```

However, `sudo apt-get install libtool` seems to fix this.

#### Cute Animal Picture


Start by reproducing the pip installation failure and inspect secp256k1/setup.py together with libsecp256k1/autogen.sh, as shown in the traceback. Confirm whether libtool is required and whether the project records that requirement in its packaging or installation guidance. Done means the dependency requirement and supported installation path are unambiguous.

Written by the indexing model from the issue text.