core, eth, trie: bloom filter for trie node dedup during fast sync (#19489)

* core, eth, trie: bloom filter for trie node dedup during fast sync

* eth/downloader, trie: address review comments

* core, ethdb, trie: restart fast-sync bloom construction now and again

* eth/downloader: initialize fast sync bloom on startup

* eth: reenable eth/62 until we properly remove it

vendor/github.com/steakknife/hamming/doc.go

@@ -0,0 +1,35 @@
+//
+// Package hamming distance calculations in Go
+//
+// https://github.com/steakknife/hamming
+//
+// Copyright © 2014, 2015, 2016, 2018 Barry Allard
+//
+// MIT license
+//
+//
+// Usage
+//
+// For functions named CountBits.+s?.  The plural forms are for slices.
+// The CountBits.+ forms are Population Count only, where the bare-type
+// forms are Hamming distance (number of bits different) between two values.
+//
+// Optimized assembly .+PopCnt forms are available on amd64, and operate just
+// like the regular forms (Must check and guard on HasPopCnt() first before
+// trying to call .+PopCnt functions).
+//
+//    import 'github.com/steakknife/hamming'
+//
+//    // ...
+//
+//    // hamming distance between values
+//    hamming.Byte(0xFF, 0x00) // 8
+//    hamming.Byte(0x00, 0x00) // 0
+//
+//    // just count bits in a byte
+//    hamming.CountBitsByte(0xA5), // 4
+//
+// Got rune? use int32
+// Got uint8? use byte
+//
+package hamming