graphics/darktable: fix broken build, data/kernels/ related
This patch is to fix this problem:
| CMake Error at data/kernels/CMakeLists.txt:34 (foreach): |
| Unknown argument: |
| /usr/ports/graphics/darktable/work/darktable-3.0.0/data/kernels/atrous.cl |
Approved by: portmgr@ (blanket approval to fix broken builds)