fix 'openssl_fips' is not defined

[yuyuko233]

fix nodejs/node-gyp#2673

error log

gyp: name 'openssl_fips' is not defined while evaluating condition 'openssl_fips != ""' in binding.gyp while trying to load binding.gyp
gyp ERR! configure error
gyp ERR! stack Error: gyp failed with exit code: 1