Lib: fix incorrect hostname check return value
Lib: fix incorrect hostname check return value

amqp_ssl_socket_verify_hostname returns 1 on success, 0 on not found,
and -1 on error. Refactor this code to be less error-prone and not use
magic numbers in return values.

Fixes #330

alanxz/rabbitmq-c,Haster2004/rabbitmq-c,Haster2004/rabbitmq-c,alanxz/rabbitmq-c,alanxz/rabbitmq-c,Haster2004/rabbitmq-c