nvcc warnings are not caught in testing

[aprokop]

Detected in #268. Warnings like

/var/jenkins/workspace/ArborX_PR-268/src/details/ArborX_Predicates.hpp(34): warning: __device__ annotation is ignored on a function("Nearest") that is explicitly defaulted on its first declaration

were not detected in Style. It seems that there is problematic interaction of nvcc_wrapper, nvcc, jenkins, etc.

[masterleinad]

We should be able to just record the compiler output manually and grep for "warning: ". That's certainly not perfect but should work as a workaround.

[aprokop]

I think a better solution would be to make Style check pick it up. The following pattern works to transform nvcc style warnings to that of gcc:

sed "s/\(.*\)(\([[:digit:]]*\)):/\1:\2:/"'

Just need to make the output transform to that in .jenkins. Quick hack did not work for me, though.

[aprokop]

We should introduce -Werror to CUDA builds.

[aprokop]

Should do it after kokkos/kokkos#7021 is resolved.