Webadmin: Added a missing CS lock.
Webadmin: Added a missing CS lock.

This fixes an assert when accessing the login-page and the plugin-failure pages in the webadmin.

Altenius/cuberite,johnsoch/cuberite,mc-server/MCServer,nounoursheureux/MCServer,Altenius/cuberite,nounoursheureux/MCServer,Altenius/cuberite,nounoursheureux/MCServer,nounoursheureux/MCServer,mc-server/MCServer,Altenius/cuberite,mc-server/MCServer,mc-server/MCServer,Altenius/cuberite,nounoursheureux/MCServer,nounoursheureux/MCServer,johnsoch/cuberite,johnsoch/cuberite,mc-server/MCServer,mc-server/MCServer,johnsoch/cuberite,johnsoch/cuberite