use snprintf in knownhost_writeline() rather then sprintf
use snprintf in knownhost_writeline() rather then sprintf

Although the function checks the length, if the code was in error, there
could potentially be a buffer overrun with the use of sprintf.  Instead replace
with snprintf.

Signed-off-by: Steven Dake <8638f3fce5db0278cfbc239bd581dfc00c29ec9d@redhat.com>

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