Fix warnings

Fix some warnings 

src/aio/poller_kqueue.inc:83:36: warning: comparison of integers of different signs: 'uintptr_t' (aka 'unsigned long') and 'int' [-Wsign-compare]
        if (self->events [i].ident == hndl->fd)
src/aio/poller_kqueue.inc:116:36: warning: comparison of integers of different signs: 'uintptr_t' (aka 'unsigned long') and 'int' [-Wsign-compare]
        if (self->events [i].ident == hndl->fd &&
src/aio/poller_kqueue.inc:150:36: warning: comparison of integers of different signs: 'uintptr_t' (aka 'unsigned long') and 'int' [-Wsign-compare]
        if (self->events [i].ident == hndl->fd &&

src/utils/efd_pipe.inc:99:29: warning: comparison of integers of different signs: 'ssize_t' (aka 'long') and 'unsigned long' [-Wsign-compare]
        if (nn_fast (nbytes < sizeof (buf)))