event/ServerSocket, doc, ...: refer to AF_LOCAL as "local socket"

.. and not "UNIX domain socket.  Be consistent about the naming.

src/event/ServerSocket.cxx

@@ -392,7 +392,7 @@ ServerSocket::AddPath(AllocatedPath &&path)
 #else /* !HAVE_UN */
 	(void)path;
 
-	throw std::runtime_error("UNIX domain socket support is disabled");
+	throw std::runtime_error("Local socket support is disabled");
 #endif /* !HAVE_UN */
 }
 

src/event/ServerSocket.hxx

@@ -90,7 +90,7 @@ public:
 	void AddHost(const char *hostname, unsigned port);
 
 	/**
-	 * Add a listener on a Unix domain socket.
+	 * Add a listener on a local socket.
 	 *
 	 * Throws #std::runtime_error on error.
 	 *