MINOR: log/backend: always free parsing hints in resolve_logger()

MINOR: log/backend: always free parsing hints in resolve_logger()

Since resolve_logger() always resolves logger target (even when error
occurs), we must take care of freeing parsing hints because free_logger()
won't try to do it if target RESOLVED flag is set on the target.

This isn't considered as a bug because resolve_logger(), being a
postparsing check, will make haproxy immediately exit upon fatal error
in haproxy.c, but it's better to ensure that everything will be properly
freed if we decide to perform a clean exit upon postparsing checks error
in the future.