libssh2_knownhost_writefile - write a collection of known hosts to a
int libssh2_knownhost_writefile(LIBSSH2_KNOWNHOSTS *hosts,
const char *filename, int type);
Writes all the known hosts to the specified file using the specified
filename specifies what filename to create
type specifies what file type it is, and LIBSSH2_KNOWNHOST_FILE_OPENSSH
is the only currently supported format.
Returns a regular libssh2 error code, where negative values are error
codes and 0 indicates success.
Added in libssh2 1.2