[release/1.4.13] core/state: track all accounts in canon state

This change introduces a global, per-state cache that keeps account data
in the canon state. Thanks to @karalabe for lots of fixes.

(cherry picked from commit a59a93f476)

core/vm/instructions.go

@@ -363,7 +363,7 @@ func opCalldataCopy(instr instruction, pc *uint64, env Environment, contract *Co
 
 func opExtCodeSize(instr instruction, pc *uint64, env Environment, contract *Contract, memory *Memory, stack *stack) {
 	addr := common.BigToAddress(stack.pop())
-	l := big.NewInt(int64(len(env.Db().GetCode(addr))))
+	l := big.NewInt(int64(env.Db().GetCodeSize(addr)))
 	stack.push(l)
 }