An improper locking due to the unreleased lock before program exit

[ycaibb]

Hi developers, in the below codes, the lock daemon could be not released before program's exit abort();. I think it is better to write MHD_ip_count_unlock (daemon); before the abort(); for better resource management and code symmetry. Thanks!

https://github.com/rboulton/libmicrohttpd/blob/61ce9c138338ed34d477482cd5efcaf1bde422dc/src/daemon/daemon.c#L333-L367