* openssl.cfg: Add OpenSSL library configuration with tests
Reference: https://www.openssl.org/docs/man1.1.1/man3/
* openssl.cfg: Add some configurations for EVP functions
Add alloc/dealloc configuration for EVP_CIPHER_CTX_new and
EVP_CIPHER_CTX_free.
Add configuration for encryption functions that are used in example code
which is added to the tests.
* libsigc++.cfg: Add configuration for library libsigc++
Reference: https://libsigcplusplus.github.io/libsigcplusplus/
* Make code compatible with libsigc++-2.0 instead of 3.0
Since Version 3.0 C++14 is required which is not (fully) supported in
some older GCC versions.
Sebastian
Daniel Marjamäki
Maksim Derbasov