Use dynamic probing

[jethrogb]

Currently, only a pre-defined set of known locations is searched. There are two more options that have a higher chance of success on systems with a custom install location:

1. Find the openssl binary and run openssl version -d
2. Find the libcrypto.so library and call SSLeay_version(SSLEAY_DIR)

[kolbma]

The thing is, that currently openssl-probe doesn't depend on openssl. It looks for ssl certs.
It is e.g. used in combination with rustls to provide tls features without openssl.