Fixing Claws-Mail TLS on macOS (Homebrew, Apple Silicon)

Claws-Mail on macOS Apple Silicon (via Homebrew) currently fails to establish TLS connections. The root cause is the way Homebrew builds and links `libetpan`, which results in broken TLS behaviour when used together with Claws on Apple Silicon. Even when GnuTLS itself works correctly, Claws aborts or reports failed handshakes. One solution that worked for me is to avoid the Homebrew-supplied…