graphdriver: temporarily ignore unsafeptr: possible misuse of reflect.SliceHeader

Probably needs a similar change as c208f03fbddb4355729c3225bb2550c4d54a2c5e,
but this code makes my head spin, so for now suppressing, and created a
tracking issue:

    daemon/graphdriver/graphtest/graphtest_unix.go:305:12: unsafeptr: possible misuse of reflect.SliceHeader (govet)
        header := *(*reflect.SliceHeader)(unsafe.Pointer(&buf))
                  ^
    daemon/graphdriver/graphtest/graphtest_unix.go:308:36: unsafeptr: possible misuse of reflect.SliceHeader (govet)
        data := *(*[]byte)(unsafe.Pointer(&header))
                                          ^

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/graphdriver/graphtest/graphtest_unix.go

@@ -302,10 +302,10 @@ func writeRandomFile(path string, size uint64) error {
 	}
 
 	// Cast to []byte
-	header := *(*reflect.SliceHeader)(unsafe.Pointer(&buf))
+	header := *(*reflect.SliceHeader)(unsafe.Pointer(&buf)) //nolint:govet // FIXME: unsafeptr: possible misuse of reflect.SliceHeader (govet) see https://github.com/moby/moby/issues/42444
 	header.Len *= 8
 	header.Cap *= 8
-	data := *(*[]byte)(unsafe.Pointer(&header))
+	data := *(*[]byte)(unsafe.Pointer(&header)) //nolint:govet // FIXME: unsafeptr: possible misuse of reflect.SliceHeader (govet) see https://github.com/moby/moby/issues/42444
 
 	return ioutil.WriteFile(path, data, 0700)
 }