remote: enforce ACL write permission for getting guest time & hostname

Getting the guest time and hostname both require use of guest agent
commands. These must not be allowed for read-only users, so the
permissions check must validate "write" permission not "read".

Fixes CVE-2019-3886
Reviewed-by: NJim Fehlig <jfehlig@suse.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/remote/remote_protocol.x

@@ -5513,7 +5513,7 @@ enum remote_procedure {
 
     /**
      * @generate: both
-     * @acl: domain:read
+     * @acl: domain:write
      */
     REMOTE_PROC_DOMAIN_GET_HOSTNAME = 277,
 
@@ -5908,7 +5908,7 @@ enum remote_procedure {
 
     /**
      * @generate: none
-     * @acl: domain:read
+     * @acl: domain:write
      */
     REMOTE_PROC_DOMAIN_GET_TIME = 337,