message: In the GNU make build system, support SUNDIALS_DIR defined using
  the path substitution.
diff: @@ -253,8 +253,9 @@ POSIX_CLOCKS_LIB = -lrt
  # and modify cmake variables for hypre for sundials
  SUNDIALS_DIR = @MFEM_DIR@/../sundials-5.0.0/instdir
  SUNDIALS_OPT = -I$(SUNDIALS_DIR)/include
  -SUNDIALS_LIBDIR = $(wildcard $(SUNDIALS_DIR)/lib*)
  -SUNDIALS_LIB = $(XLINKER)-rpath,$(SUNDIALS_LIBDIR) -L$(SUNDIALS_LIBDIR)\
  +SUNDIALS_LIB = $(XLINKER)-rpath,$(SUNDIALS_DIR)/lib64\
  + $(XLINKER)-rpath,$(SUNDIALS_DIR)/lib\
  + -L$(SUNDIALS_DIR)/lib64 -L$(SUNDIALS_DIR)/lib\
  -lsundials_arkode -lsundials_cvodes -lsundials_nvecserial -lsundials_kinsol
  ifeq ($(MFEM_USE_MPI),YES)
  