[INFRA] Import NVIDIA/CCCL upstream as optimization reference library

CCCL (CUDA C++ Core Libraries) provides:
- CUB: device/block/warp-level GPU primitives (reduce, scan, sort, topk)
- Thrust: high-level parallel algorithms (transform_reduce, sort, scan)
- libcudacxx: CUDA C++ standard library (atomics, barriers, memory)
- cudax: experimental features (memory resources, allocators)
- Tuning policies: per-SM hardware-specific algorithm parameters

Competition optimization vectors mapped to CCCL:
- Output TPS (83% weight): warp_reduce, block_reduce, device_topk
- Input TPS (14% weight): device_scan, block_load, prefetch
- Cache TPS (3% weight): prefix caching strategy patterns
- Memory (0.9 util): pooled/cached/buddy allocators

Source: https://github.com/NVIDIA/cccl (shallow clone, HEAD only)
License: Apache-2.0

cccl_upstream/thrust/testing/cmake/CMakeLists.txt

@@ -0,0 +1,10 @@
+# Check source code for issues that can be found by pattern matching:
+add_test(
+  NAME thrust.test.cmake.check_source_files
+  # gersemi: off
+  COMMAND
+    "${CMAKE_COMMAND}"
+      -D "Thrust_SOURCE_DIR=${Thrust_SOURCE_DIR}"
+      -P "${CMAKE_CURRENT_LIST_DIR}/check_source_files.cmake"
+  # gersemi: on
+)