message: In unit tets makefile, check for cuda using MFEM_USE_CUDA
  instead of comparing MFEM_CXX == nvcc.
  This resolves an issue where the cuda tests are not build and
  run when MFEM_CXX uses the full path to nvcc.
diff: @@ -35,20 +35,21 @@ PAR_MAIN_OBJ = punit_test_main.o
  # Sedov numerical seq/par files and tests
  SEDOV_FILES = $(SRC)miniapps/test_sedov.cpp
  +USE_CUDA := $(MFEM_USE_CUDA:NO=)
  SEQ_SEDOV_TESTS = sedov_tests_cpu sedov_tests_debug
  -SEQ_SEDOV_TESTS += $(if $(MFEM_CXX:nvcc=),,sedov_tests_cuda)
  -SEQ_SEDOV_TESTS += $(if $(MFEM_CXX:nvcc=),,sedov_tests_cuda_uvm)
  +SEQ_SEDOV_TESTS += $(if $(USE_CUDA),sedov_tests_cuda)
  +SEQ_SEDOV_TESTS += $(if $(USE_CUDA),sedov_tests_cuda_uvm)
  PAR_SEDOV_TESTS = $(SEQ_SEDOV_TESTS:%=p%)
  SEQ_SEDOV_CPU_OBJ_FILES = $(SEDOV_FILES:$(SRC)%.cpp=%.cpu.o)
  SEQ_SEDOV_DEBUG_OBJ_FILES = $(SEDOV_FILES:$(SRC)%.cpp=%.debug.o)
  -SEQ_SEDOV_CUDA_OBJ_FILES = $(if $(MFEM_CXX:nvcc=),,$(SEDOV_FILES:$(SRC)%.cpp=%.cuda.o))
  -SEQ_SEDOV_CUDA_UVM_OBJ_FILES = $(if $(MFEM_CXX:nvcc=),,$(SEDOV_FILES:$(SRC)%.cpp=%.cuda_uvm.o))
  +SEQ_SEDOV_CUDA_OBJ_FILES = $(if $(USE_CUDA),$(SEDOV_FILES:$(SRC)%.cpp=%.cuda.o))
  +SEQ_SEDOV_CUDA_UVM_OBJ_FILES = $(if $(USE_CUDA),$(SEDOV_FILES:$(SRC)%.cpp=%.cuda_uvm.o))
  PAR_SEDOV_CPU_OBJ_FILES = $(SEDOV_FILES:$(SRC)%.cpp=%.pcpu.o)
  PAR_SEDOV_DEBUG_OBJ_FILES = $(SEDOV_FILES:$(SRC)%.cpp=%.pdebug.o)
  -PAR_SEDOV_CUDA_OBJ_FILES = $(if $(MFEM_CXX:nvcc=),,$(SEDOV_FILES:$(SRC)%.cpp=%.pcuda.o))
  -PAR_SEDOV_CUDA_UVM_OBJ_FILES = $(if $(MFEM_CXX:nvcc=),,$(SEDOV_FILES:$(SRC)%.cpp=%.pcuda_uvm.o))
  +PAR_SEDOV_CUDA_OBJ_FILES = $(if $(USE_CUDA),$(SEDOV_FILES:$(SRC)%.cpp=%.pcuda.o))
  +PAR_SEDOV_CUDA_UVM_OBJ_FILES = $(if $(USE_CUDA),$(SEDOV_FILES:$(SRC)%.cpp=%.pcuda_uvm.o))
  SEQ_UNIT_TESTS = unit_tests $(SEQ_SEDOV_TESTS)
  PAR_UNIT_TESTS = punit_tests $(PAR_SEDOV_TESTS)
  