[libvirt] Fix compile errors in 'safezero()' functions in util.c

Hi! Fix compile errors in 'safezero()' functions in util.c Commit 70e7672184ff639856d5f2f3bf7849464031dff9 introduced some compile errors because of the unsued 'flags' parameter in all three version of the 'safezero()' function. Signed-Off-By: Maximilian Wilhelm <max@rfc2324.org> The attached patch fixes this. Ciao Max -- Follow the white penguin.