Added initial CUDA backend stub.

src/backend/cuda/cuda.cmake

@@ -0,0 +1,23 @@
+if (WITH_CUDA)
+    add_definitions(/DXMRIG_FEATURE_CUDA)
+
+    set(HEADERS_BACKEND_CUDA
+        src/backend/cuda/CudaBackend.h
+        src/backend/cuda/CudaConfig.h
+        src/backend/cuda/CudaConfig_gen.h
+        src/backend/cuda/CudaThread.h
+        src/backend/cuda/CudaThreads.h
+       )
+
+    set(SOURCES_BACKEND_CUDA
+        src/backend/cuda/CudaBackend.cpp
+        src/backend/cuda/CudaConfig.cpp
+        src/backend/cuda/CudaThread.cpp
+        src/backend/cuda/CudaThreads.cpp
+       )
+else()
+    remove_definitions(/DXMRIG_FEATURE_CUDA)
+
+    set(HEADERS_BACKEND_CUDA "")
+    set(SOURCES_BACKEND_CUDA "")
+endif()