Memory leak in mountd

In client_compose(), free() the hostent structure returned before
exiting. Normally, gethostbyaddr() returns a pointer to a static
struct, but this hostent comes from either get_reliable_hostbyaddr() or
get_hostent(), both which return a pointer they privately xmalloc()ed,
which thus can and should be free()d.

Signed-Off-By: Steinar H. Gunderson <sesse@debian.org>