scrypt-1.2.0/libcperciva/crypto/crypto_aes.c:6:10: fatal error: 'openssl/aes.h' file not found #209

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Checklist

• installed pyethapp inside a virtualenv

System/environment

• OS: macOS Sierra 10.12.3
• python version: 2.7.12
• pyethapp version: can't install successfully
• installation method (pip & pypi/git & setup.py): pip install pyethapp
• pyethapp branch (if applicable): FIXME

Expected behaviour

Uh...maybe Done!

Observed behaviour

....
scrypt-1.2.0/libcperciva/crypto/crypto_aes.c:6:10: fatal error: 'openssl/aes.h' file not found
#include <openssl/aes.h>
^
1 error generated.
error: command '/usr/bin/clang' failed with exit status 1

----------------------------------------
Command "/Users/Crayon_277/Develop/Ethereum/pyethapp/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/py/0gqprtwx2wd_zvrlz6hlq2r40000gn/T/pip-build-PtHskm/scrypt/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/py/0gqprtwx2wd_zvrlz6hlq2r40000gn/T/pip-feLEKw-record/install-record.txt --single-version-externally-managed --compile --install-headers /Users/Crayon_277/Develop/Ethereum/pyethapp/bin/../include/site/python2.7/scrypt" failed with error code 1 in /private/var/folders/py/0gqprtwx2wd_zvrlz6hlq2r40000gn/T/pip-build-PtHskm/scrypt

Steps to reproduce

FIXME