Import: Fix incorrect wfRunHooks usage

af125df5199b5c232bf335d735cecc6d8f8e9784 broke importing
because Import.php was calling wfRunHooks() improperly.
Fixing the calls and making the wfRunHooks() signature
match Hooks::run() to make call errors immediately detectable.

Change-Id: If44292fedf6917cde1dae7f0391231a18d414610