[mlir][bazel] Don't set MLIR_ENABLE_NVPTXCOMPILER on if_cuda_available.

was available. However, it turns out that the NVPTX compiler is not part
of every CUDA distribution, so `if_cuda_available` may evaluate to true
without that compiler being present, which breaks the build. This PR
thus sets the macro to 0 always (which was the behavior before llvm#84007).

Author: ingomueller-net

utils/bazel/llvm-project-overlay/mlir/BUILD.bazel

@@ -35,17 +35,12 @@ expand_template(
         "#cmakedefine01 MLIR_DEPRECATED_GPU_SERIALIZATION_ENABLE": "#define MLIR_DEPRECATED_GPU_SERIALIZATION_ENABLE 0",
         "#cmakedefine01 MLIR_ENABLE_EXPENSIVE_PATTERN_API_CHECKS": "#define MLIR_ENABLE_EXPENSIVE_PATTERN_API_CHECKS 0",
         "#cmakedefine MLIR_GREEDY_REWRITE_RANDOMIZER_SEED ${MLIR_GREEDY_REWRITE_RANDOMIZER_SEED}": "/* #undef MLIR_GREEDY_REWRITE_RANDOMIZER_SEED */",
+        "#cmakedefine01 MLIR_ENABLE_NVPTXCOMPILER": "#define MLIR_ENABLE_NVPTXCOMPILER 0",
         "#cmakedefine01 MLIR_ENABLE_PDL_IN_PATTERNMATCH": "#define MLIR_ENABLE_PDL_IN_PATTERNMATCH 1",
         "#cmakedefine01 MLIR_ENABLE_ROCM_CONVERSIONS": "#define MLIR_ENABLE_ROCM_CONVERSIONS 0",
     } | if_cuda_available(
-        {
-            "#cmakedefine01 MLIR_ENABLE_CUDA_CONVERSIONS": "#define MLIR_ENABLE_CUDA_CONVERSIONS 1",
-            "#cmakedefine01 MLIR_ENABLE_NVPTXCOMPILER": "#define MLIR_ENABLE_NVPTXCOMPILER 1",
-        },
-        {
-            "#cmakedefine01 MLIR_ENABLE_CUDA_CONVERSIONS": "#define MLIR_ENABLE_CUDA_CONVERSIONS 0",
-            "#cmakedefine01 MLIR_ENABLE_NVPTXCOMPILER": "#define MLIR_ENABLE_NVPTXCOMPILER 0",
-        },
+        {"#cmakedefine01 MLIR_ENABLE_CUDA_CONVERSIONS": "#define MLIR_ENABLE_CUDA_CONVERSIONS 1"},
+        {"#cmakedefine01 MLIR_ENABLE_CUDA_CONVERSIONS": "#define MLIR_ENABLE_CUDA_CONVERSIONS 0"},
     ),
     template = "include/mlir/Config/mlir-config.h.cmake",
 )