Installation issue with CUDA 10 + Gcc8

@mark As reported in this issue, https://github.com/LLNL/blt/issues/341, check for working CUDA compiler fails (Cuda10 + Gcc8). I solved on Marconi100 by adding -DCMAKE_CUDA_FLAGS="-std=c++11" to cmakeOpts

cmakeOpts="-DCMAKE_INSTALL_PREFIX=$CMAKE_INSTALL_PREFIX -DCMAKE_CUDA_FLAGS="-std=c++11""