Add XO_CONTEXT_CUDA flag

Author: szymonlopaciuk

xobjects/context_cupy.py

@@ -455,6 +455,7 @@ def build_kernels(
             with open(save_source_as, "w") as fid:
                 fid.write(specialized_source)
 
+        extra_compile_args = (*extra_compile_args, "-DXO_CONTEXT_CUDA")
         module = cupy.RawModule(code=specialized_source, options=extra_compile_args)
 
         out_kernels = {}