Use --with-openssl-rpath flag when building Python

[mscastanho]

Python 3.10 added a new --with-openssl-rpath flag to improve the detection of a custom OpenSSL insallation (python/cpython@32eba61).

We may need to use it on AT next (future 16) to make sure we are using AT's OpenSSL and not the system's when building Python.

[mscastanho]

Some related bugs that contain more info about this flag and the issues it solves:
https://bugs.python.org/issue43466
https://bugs.python.org/issue34028

[tuliom]

I am skeptical of setting RPATH or RUNPATH for executables or libraries built with AT. It shouldn't be necessary.
It sounds like a workaround to another kind of issue.