Add the CUDA samples include dir to the path for tests

Means we get to easily steal CUDA examples for tests


[ROCm/hip commit: 71aa7e267a]

projects/hip/tests/hipify-clang/lit.cfg

@@ -47,5 +47,5 @@ if obj_root is not None:
 config.substitutions.append(("hipify", obj_root+"/hipify-clang"))
 
 # Clang args for CUDA...
-config.substitutions.append(("%cuda_args", "-x cuda --cuda-path=%s --cuda-gpu-arch=sm_30" % config.cuda_root))
+config.substitutions.append(("%cuda_args", "-x cuda --cuda-path=%s --cuda-gpu-arch=sm_30 -isystem%s/samples/common/inc" % (config.cuda_root, config.cuda_root)))
 config.substitutions.append(("%run_test", config.test_source_root + "/run_test.sh"))