avoid uninitialized access to next_thermo and next_restart from reset_dt()

src/output.cpp

@@ -77,7 +77,7 @@ Output::Output(LAMMPS *lmp) : Pointers(lmp)
   ndump = 0;
   max_dump = 0;
   any_time_dumps = 0;
-  next_dump_any = next_time_dump_any = MAXBIGINT;
+  next_thermo = next_restart = next_dump_any = next_time_dump_any = MAXBIGINT;
   mode_dump = nullptr;
   every_dump = nullptr;
   every_time_dump = nullptr;