Allow auto suggestion for subpages of some special pages
The autocomplete search allows special pages to define the list of
subpages to be excepted. Fill up the function to show auto suggestion
for subpages of the following special pages:
Special:AllPages
Special:ChangeContentModel
Special:FileDuplicateSearch
Special:Movepage
Special:PageLanguage
Special:Prefixindex
Special:Recentchangeslinked
Special:Undelete
This makes it easier to navigate to this special pages with a prefilled
title/target field.
Change-Id: I71f77c3001a12d75b901807c20115cead9c64e93