_libssh2_wait_socket: detect nothing-to-wait-for
_libssh2_wait_socket: detect nothing-to-wait-for

If _libssh2_wait_socket() gets called but there's no direction set to
wait for, this causes a "hang". This code now detects this situation,
set a 1 second timeout instead and outputs a debug output about it.

libssh2/libssh2,libssh2/libssh2,libssh2/libssh2,libssh2/libssh2