Allow usage of xCache variable cache if xcache_unset_by_prefix() is present.
Allow usage of xCache variable cache if xcache_unset_by_prefix() is present.

whitekiba/server,andreas-p/nextcloud-server,xx621998xx/server,pollopolea/core,xx621998xx/server,pixelipo/server,owncloud/core,owncloud/core,michaelletzgus/nextcloud-server,whitekiba/server,Ardinis/server,lrytz/core,pixelipo/server,andreas-p/nextcloud-server,cernbox/core,bluelml/core,cernbox/core,whitekiba/server,lrytz/core,pixelipo/server,endsguy/server,nextcloud/server,xx621998xx/server,endsguy/server,cernbox/core,andreas-p/nextcloud-server,jbicha/server,IljaN/core,bluelml/core,jbicha/server,sharidas/core,michaelletzgus/nextcloud-server,phil-davis/core,jbicha/server,jbicha/server,sharidas/core,bluelml/core,pixelipo/server,pollopolea/core,Ardinis/server,bluelml/core,Ardinis/server,nextcloud/server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,lrytz/core,endsguy/server,pmattern/server,owncloud/core,lrytz/core,xx621998xx/server,cernbox/core,IljaN/core,endsguy/server,whitekiba/server,Ardinis/server,pmattern/server,IljaN/core,sharidas/core,pmattern/server,jbicha/server,andreas-p/nextcloud-server,IljaN/core,IljaN/core,owncloud/core,pmattern/server,pollopolea/core,pmattern/server,Ardinis/server,bluelml/core,sharidas/core,cernbox/core,pollopolea/core,nextcloud/server,lrytz/core,pixelipo/server,whitekiba/server,xx621998xx/server,sharidas/core,pollopolea/core,owncloud/core,michaelletzgus/nextcloud-server,nextcloud/server,endsguy/server