message: add libstanmath_mpi to makefile
diff: @@ -83,6 +83,7 @@ CXX = $(CC)
  -include $(MATH)make/detect_os
  -include $(MATH)make/setup_mpi
  +-include $(MATH)make/libstanmath_mpi # $(MATH)bin/libstanmath_mpi.a
  include make/libstan # libstan.a
  include make/models # models
  