depmod: add asserts to ensure positive return from ftell()
depmod: add asserts to ensure positive return from ftell()

Also ignore some errors that will later be returned by ferror().

lucasdemarchi/kmod,pmmccorm/kmod,pmmccorm/kmod,pmmccorm/kmod,lucasdemarchi/kmod,lpereira/kmod,lpereira/kmod,Distrotech/kmod,Distrotech/kmod,lucasdemarchi/kmod,lpereira/kmod,Distrotech/kmod