unit tests failing/hanging on Volta

[ndellingwood]

The following unit test hangs when running on Volta with Cuda 9.1:

cuda.sparse_spgemm_double_int_int_TestExecSpace

[ndellingwood]

This test failed on Apollo with Cuda 9.1 + gcc/6.1
cuda.graph_graph_color_d2_double_int_int_TestExecSpace

Output:

[ RUN      ] cuda.graph_graph_color_d2_double_int_int_TestExecSpace
/home/ndellin/kokkos-kernels/unit_test/graph/Test_Graph_graph_color_d2.hpp:209: Failure
Value of: (num_conflict == conf)
  Actual: false
Expected: true
/home/ndellin/kokkos-kernels/unit_test/graph/Test_Graph_graph_color_d2.hpp:211: Failure
Value of: (num_conflict == 0)
  Actual: false
Expected: true
/home/ndellin/kokkos-kernels/unit_test/graph/Test_Graph_graph_color_d2.hpp:209: Failure
Value of: (num_conflict == conf)
  Actual: false
Expected: true
/home/ndellin/kokkos-kernels/unit_test/graph/Test_Graph_graph_color_d2.hpp:211: Failure
Value of: (num_conflict == 0)
  Actual: false
Expected: true
[  FAILED  ] cuda.graph_graph_color_d2_double_int_int_TestExecSpace (461 ms)

[ndellingwood]

Renamed the issue to collect test failures/hangs on Volta

[mhoemmen]

@micahahoward

[ndellingwood]

PR #201 merged with @mndevec 's fix