provisioners/docker: configure autostart works if OS can't check status

plugins/provisioners/docker/cap/debian/docker_configure_auto_start.rb

@@ -13,10 +13,16 @@ module VagrantPlugins
                 # Wait some amount time for the pid to become available
                 # so that we don't start executing Docker commands until
                 # it is available.
+                if machine.guest.capability?(:docker_daemon_running)
                   [0, 1, 2, 4].each do |delay|
                     sleep delay
                     break if machine.guest.capability(:docker_daemon_running)
                   end
+                else
+                  # This OS doesn't support checking if Docker is running,
+                  # so just wait 5 seconds.
+                  sleep 5
+                end
               end
             end
           end