wallet: Close dbenv error file db.log

The error file db.log is opened by BerkeleyEnvironment instance and
should be closed after dbenv is closed.

Author: promag

src/wallet/db.cpp

@@ -126,11 +126,16 @@ void BerkeleyEnvironment::Close()
         }
     }
 
+    FILE* error_file = nullptr;
+    dbenv->get_errfile(&error_file);
+
     int ret = dbenv->close(0);
     if (ret != 0)
         LogPrintf("BerkeleyEnvironment::Close: Error %d closing database environment: %s\n", ret, DbEnv::strerror(ret));
     if (!fMockDb)
         DbEnv((u_int32_t)0).remove(strPath.c_str(), 0);
+
+    if (error_file) fclose(error_file);
 }
 
 void BerkeleyEnvironment::Reset()