Randomize extra_nonce

To guarantee that hashing blobs will be different between different p2pool nodes, even if they mine to the same wallet address and don't have transactions to shuffle within the block template.

src/miner.cpp

@@ -25,6 +25,7 @@
 #include "params.h"
 #include "p2pool_api.h"
 #include "side_chain.h"
+#include "p2p_server.h"
 #include <thread>
 
 static constexpr char log_category_prefix[] = "Miner ";
@@ -40,7 +41,7 @@ Miner::Miner(p2pool* pool, uint32_t threads)
 	, m_startTimestamp(high_resolution_clock::now())
 	, m_nonce(0)
 	, m_nonceTimestamp(m_startTimestamp)
-	, m_extraNonce(0xF19E3779U)
+	, m_extraNonce(static_cast<uint32_t>(pool->p2p_server()->get_random64()))
 	, m_totalHashes(0)
 	, m_sharesFound(0)
 	, m_job{}