Installation failure with macOS, Homebrew OpenSSL

[zachriggle]

proofofwork fails to install out-of-the-box on macOS due to missing OpenSSL libraries.

OpenSSL is installed on my system with brew install openssl.

In order for the build to succeed, the command must be invoked a la:

$ CFLAGS='-I/usr/local/opt/openssl/include' pip install --user proofofwork

It may be useful to check for this missing flag on macOS, and set the appropriate environment variable if that directory exists.

[kmyk]

Thank you for reporting.
I'm trying to make a patch for this, but I have no environment to reproduce this problem.

@zachriggle Can you help me with testing this patch 34867e4 ? Please run commands below, check the results, and give me the log if these failed.

$ git clone libproofofwork
$ cd libproofofwork
$ git checkout fix/21
$ cmake .
$ make