fix: add /Zc:preprocessor for MSVC with CUDA 13.2+

CUDA 13.2's CCCL headers require MSVC's standard conforming
preprocessor. Pass /Zc:preprocessor to cl.exe via -Xcompiler.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Titus-von-Koeller

CMakeLists.txt

@@ -194,6 +194,11 @@ if(BUILD_CUDA)
         string(APPEND CMAKE_CUDA_FLAGS " --compress-mode=size")
     endif()
 
+    # CUDA 13.2+ CCCL headers require MSVC's standard conforming preprocessor.
+    if(MSVC AND CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL "13.2")
+        string(APPEND CMAKE_CUDA_FLAGS " -Xcompiler=/Zc:preprocessor")
+    endif()
+
     if(PTXAS_VERBOSE)
         string(APPEND CMAKE_CUDA_FLAGS " -Xptxas=-v")
     endif()