Check for existing -ccbin / --compiler-bindir flag in NVCC_PREPEND_FLAGS

[jakirkham]

As a user can include their own -ccbin / --compiler-bindir flags that would conflict with our flags added to NVCC_PREPEND_FLAGS (see below), it would be good to add a check to only add our flags if they are not -ccbin / --compiler-bindir in NVCC_PREPEND_FLAGS

cuda-nvcc-feedstock/recipe/activate.sh

Line 38 in f602ed9

NVCC_PREPEND_FLAGS="${NVCC_PREPEND_FLAGS} -ccbin=${CXX}"

In the nvcc wrapper script, this was handled on this line. Though --compiler-bindir is not checked. So maybe that logic can be adapted and tweaked here.

Edit: Originally came up in PR ( conda-forge/gromacs-feedstock#17 )