cuda.scatterview unit test causes "Bus error" when force_uvm and enable_lambda are enabled

[ndellingwood]

Tested with SHAs 21e5f5b and a76b5c1

Tested on White on the Kepler queue.

Sample error output:

[ RUN      ] cuda.scatterview
Bus error (core dumped)
bash-4.2$ 

generate_makefile reproducer:
../../generate_makefile.bash --with-cuda --with-serial --compiler=${HOME}/kokkos/bin/nvcc_wrapper --with-cuda-options="force_uvm,enable_lambda" --arch="Power8,Kepler37"

[ndellingwood]

Running the scatterview test with uvm and lambda require setting CUDA_LAUNCH_BLOCKING=1 and CUDA_MANAGED_FORCE_DEVICE_ALLOC=1 allows the test to pass.
@ibaned @crtrott are these environment variables supposed to be required, or does needing these to make the test pass an indication of an issue?

[crtrott]

This is a bug basically there is a missing Kokkos::fence()

[crtrott]

Bug is in the test not in the code.

[crtrott]

PR #1854

[ndellingwood]

See PR #1854.