Cleanup: better OpenSSL detection

Cleanup: better OpenSSL detection

* remove duplicate header files detection

* remove hard dependency on pkg-config. Use library ABI checks if
  pkg-config is unavailable or broken.

* remove unnecessary if conditions by using proper nesting in the event
  user does NOT provide a custom location for the library.

* produce a hard error if OpenSSL is required by user but not found.

* always list all library objects in configure final decision output.