Removed unused function argument from Window.as_sql().
Removed unused function argument from Window.as_sql().

Unused since its introduction in d549b8805053d4b064bf492ba90e90db5d7e2a6b.
wkschwartz/django,georgemarshall/django,dsanders11/django,koordinates/django,claudep/django,pauloxnet/django,solarissmoke/django,freakboy3742/django,adamchainz/django,wkschwartz/django,elena/django,rsalmaso/django,manhhomienbienthuy/django,kaedroho/django,timgraham/django,claudep/django,MarkusH/django,theo-l/django,pauloxnet/django,ghickman/django,felixxm/django,blighj/django,MarkusH/django,MarkusH/django,elena/django,georgemarshall/django,frankvdp/django,googleinterns/django,pauloxnet/django,timgraham/django,EmadMokhtar/Django,koordinates/django,ghickman/django,blighj/django,takis/django,takis/django,solarissmoke/django,EmadMokhtar/Django,adamchainz/django,wkschwartz/django,apollo13/django,auvipy/django,EmadMokhtar/Django,rsalmaso/django,atul-bhouraskar/django,ghickman/django,solarissmoke/django,auvipy/django,koordinates/django,googleinterns/django,atul-bhouraskar/django,charettes/django,fenginx/django,googleinterns/django,fenginx/django,felixxm/django,shaib/django,frankvdp/django,georgemarshall/django,shaib/django,claudep/django,monetate/django,dsanders11/django,auvipy/django,dsanders11/django,freakboy3742/django,claudep/django,apollo13/django,takis/django,django/django,ghickman/django,kaedroho/django,freakboy3742/django,shaib/django,simonw/django,kaedroho/django,simonw/django,theo-l/django,schinckel/django,blighj/django,MarkusH/django,frankvdp/django,django/django,apollo13/django,manhhomienbienthuy/django,blighj/django,manhhomienbienthuy/django,solarissmoke/django,simonw/django,schinckel/django,timgraham/django,manhhomienbienthuy/django,felixxm/django,koordinates/django,dsanders11/django,atul-bhouraskar/django,shaib/django,fenginx/django,adamchainz/django,monetate/django,timgraham/django,django/django,charettes/django,auvipy/django,googleinterns/django,rsalmaso/django,schinckel/django,elena/django,schinckel/django,apollo13/django,pauloxnet/django,elena/django,rsalmaso/django,felixxm/django,django/django,monetate/django,charettes/django,takis/django,frankvdp/django,georgemarshall/django,atul-bhouraskar/django,monetate/django,theo-l/django,simonw/django,adamchainz/django,wkschwartz/django,fenginx/django,theo-l/django,charettes/django