[VirtualBox/f25] (3 commits) ...Update VBox to 5.1.22
Summary of changes:
4becef1... Build pdf doc on f26+ (*)
c1b7442... Remove Plague-specific weirdness with EOL of RHEL5 (*)
a5ee8b4... Update VBox to 5.1.22 (*)
(*) This commit already existed in another branch; no separate mail sent