tests: Add missing locks to tests

Add missing locks to tests to satisfy lock requirements (such as
EXCLUSIVE_LOCKS_REQUIRED(...) (Clang Thread Safety Analysis),
AssertLockHeld(...) and implicit lock assumptions).

src/test/test_bitcoin.cpp

@@ -149,7 +149,10 @@ TestChain100Setup::CreateAndProcessBlock(const std::vector<CMutableTransaction>&
         block.vtx.push_back(MakeTransactionRef(tx));
     // IncrementExtraNonce creates a valid coinbase and merkleRoot
     unsigned int extraNonce = 0;
-    IncrementExtraNonce(&block, chainActive.Tip(), extraNonce);
+    {
+        LOCK(cs_main);
+        IncrementExtraNonce(&block, chainActive.Tip(), extraNonce);
+    }
 
     while (!CheckProofOfWork(block.GetHash(), block.nBits, chainparams.GetConsensus())) ++block.nNonce;