consensus/ethash: only use *reflect.SliceHeader, not reflect.SliceHea…

…der. See comment here: https://github.com/golang/go/issues/40397\#issuecomment-663748689

consensus/ethash/algorithm.go

@@ -151,10 +151,10 @@ func generateCache(dest []uint32, epoch uint64, seed []byte) {
 		logFn("Generated ethash verification cache", "elapsed", common.PrettyDuration(elapsed))
 	}()
 	// Convert our destination slice to a byte buffer
-	header := *(*reflect.SliceHeader)(unsafe.Pointer(&dest))
+	header := (*reflect.SliceHeader)(unsafe.Pointer(&dest))
 	header.Len *= 4
 	header.Cap *= 4
-	cache := *(*[]byte)(unsafe.Pointer(&header))
+	cache := *(*[]byte)(unsafe.Pointer(header))
 
 	// Calculate the number of theoretical rows (we'll store in one buffer nonetheless)
 	size := uint64(len(cache))