message: Add dependency on ex18.hpp
  Thanks
diff: @@ -37,6 +37,9 @@ endif
  # Remove built-in rule
  %: %.cpp
  +# Additional dependencies
  +ex18 ex18p: ex18.hpp
  +
  # Replace the default implicit rule for *.cpp files
  %: $(SRC)%.cpp $(MFEM_LIB_FILE) $(CONFIG_MK)
  $(MFEM_CXX) $(MFEM_FLAGS) $< -o $@ $(MFEM_LIBS)
  