Compiler helpers for build system, not host.
Add serenity as OS type in Alpine.
Add Alpine system configuration file that specifies location of CA certificates.
The system-certs-file configuration option is provided to SSL_CTX_load_verify_locations() as the CAfile argument (via imap/src/osdep/unix/ssl_unix.c).
system-certs-file and CAfile are used (as opposed to system-certs-path and CApath, used to specify a directory) because certificate files within the CApath directory must follow a specific naming convention, where the filename matches the CA subject name hash value.
See man 3 SSL_CTX_set_default_verify_paths for details on how OpenSSL looks up CA certificates. https://www.openssl.org/docs/man3.0/man3/SSL_CTX_set_default_verify_paths.html