Fix some edge cases
- SSL: support OpenSSL installations in non standard locations (cmake)
- SSL: show OpenSSL include directory in buildlog (cmake)
- SSL: remove -Wunused-value warning for SSL_CTX_set_ecdh_auto dispayed on some systems
- SIGNING: ensure a missing signing certificate is created on first build (cmake)
- SIGNING: fix filtering oscam-signing.[c|h] when WITH_SIGNING is disabled (cmake)
- LIBDVBCSA: fix link filename (cmake)
- LIBDL: link libdl by default for Linux as it is required by some systems (cmake)
- CONFIG: Fix display of configured values