Since I8d825eb02c69cc66d90bd41325133fd3f99f0226, modification of the
$cond parameter to the ModifyExportDisplayQuery hook has had no effect,
since $cond is now incorporated into a condition array $conds. This
seems contrary to the purpose of the hook, although no extension in
CodeSearch actually depends on it.
It was also a documentation error, with the incorrect type on the
interface causing a Phan error in the HookRunner call site migration
patch.
So, add a $conds parameter to the hook, which allows modification of
the array, and fix the documentation.
Change-Id: Id4608cec35df56456d7dad4de107bbef816e964b
2bcabb0dee