Mainly done because of this in all-packages.nix:
````
cipherscan = callPackage ../tools/security/cipherscan {
openssl = if stdenv.system == "x86_64-linux"
then openssl-chacha
else openssl;
};
````
... and inside cipherscan we want to refer to `openssl.bin`
CipherScan is a simple way to find out which SSL ciphersuites are
supported by a target.
It can take advantage of the extra features in Peter Mosmans' openssl
fork (which is also included in this commit).
