Bugs in SSH module (ssh.c)

I installed gcc-8&libssh* on my Ubuntu 18.04 arm64.When I was compiling any version of qemu like 3.1.0 4.0.0or 4.1.0 with SSH support,the GCC went wrong.It said some vars undeclared like'SSH_KNOWN_HOSTS_OTHER','SSH_KNOWN_HOST_UNKNOWN',etc.