clang-tidy: Add performance-inefficient-vector-operation check

https://clang.llvm.org/extra/clang-tidy/checks/performance/inefficient-vector-operation.html

src/bitcoin-util.cpp

@@ -127,6 +127,7 @@ static int Grind(const std::vector<std::string>& args, std::string& strPrint)
 
     std::vector<std::thread> threads;
     int n_tasks = std::max(1u, std::thread::hardware_concurrency());
+    threads.reserve(n_tasks);
     for (int i = 0; i < n_tasks; ++i) {
         threads.emplace_back(grind_task, nBits, header, i, n_tasks, std::ref(found), std::ref(proposed_nonce));
     }