refactor(Difftest): refactor display with c++11 features (#617)

Author: cz4e

src/test/csrc/difftest/difftest.cpp

@@ -1710,7 +1710,9 @@ void DiffState::display(int coreid) {
   Info("\n============== Commit Group Trace (Core %d) ==============\n", coreid);
   int group_index = 0;
   while (!retire_group_queue.empty()) {
-    auto [pc, cnt] = retire_group_queue.front();
+    auto retire_group = retire_group_queue.front();
+    auto pc = retire_group.first;
+    auto cnt = retire_group.second;
     retire_group_queue.pop();
     Info("commit group [%02d]: pc %010lx cmtcnt %d%s\n", group_index, pc, cnt,
          retire_group_queue.empty() ? " <--" : "");

src/test/csrc/difftest/difftest.h

@@ -190,7 +190,7 @@ class DiffState {
     if (retire_group_queue.size() >= DEBUG_GROUP_TRACE_SIZE) {
       retire_group_queue.pop();
     }
-    retire_group_queue.push({pc, count});
+    retire_group_queue.push(std::make_pair(pc, count));
   }
   void record_inst(uint64_t pc, uint32_t inst, uint8_t en, uint8_t dest, uint64_t data, bool skip, bool delayed,
                    uint8_t lqidx, uint8_t sqidx, uint16_t robidx, uint8_t isLoad, uint8_t isStore) {