Docker build error (#221)

### What problem were solved in this pull request?

Issue Number: ref #205 

Problem:
build failed on docker container

### What is changed and how it works?
fix compile error

### Other information

src/observer/storage/trx/mvcc_trx.cpp

@@ -85,7 +85,12 @@ Trx *MvccTrxKit::create_trx(int32_t trx_id)
 void MvccTrxKit::destroy_trx(Trx *trx)
 {
   lock_.lock();
-  erase(trxes_, trx);
+  for (auto iter = trxes_.begin(), itend = trxes_.end(); iter != itend; ++iter) {
+    if (*iter == trx) {
+      trxes_.erase(iter);
+      break;
+    }
+  }
   lock_.unlock();
 
   delete trx;