Disable security key for bigendian interop.

It doesn't currently work.  It's not clear why, but I suspect
sk-dummy.so ends up being built for the wrong architecture.

.github/configs

@@ -266,6 +266,10 @@ case "${TARGET_HOST}" in
 	# Native linker is not great with PIC so OpenSSL is built w/out.
 	CONFIGFLAGS="${CONFIGFLAGS} --disable-security-key"
 	;;
+    fbsd14-ppc64)
+	# Disable security key tests for bigendian interop test.
+	CONFIGFLAGS="${CONFIGFLAGS} --disable-security-key"
+	;;
     hurd)
 	SKIP_LTESTS="forwarding multiplex proxy-connect hostkey-agent agent-ptrace"
 	;;