[libc] Disable testing for NVPTX debug builds (#86856)

Summary:
Debug builds don't optimize out certain parts of the code that end up
making the GPU backend crash. This results in regular builds not being
successful just to build the testing objects. Disable them for now in
debug mode.

Author: jhuber6

libc/cmake/modules/prepare_libc_gpu_build.cmake

@@ -93,6 +93,11 @@ else()
 endif()
 set(LIBC_GPU_TARGET_ARCHITECTURE "${gpu_test_architecture}")
 
+# The NVPTX backend cannot currently handle objects created in debug mode.
+if(LIBC_TARGET_ARCHITECTURE_IS_NVPTX AND CMAKE_BUILD_TYPE STREQUAL "Debug")
+  set(LIBC_GPU_TESTS_DISABLED TRUE)
+endif()
+
 # Identify the GPU loader utility used to run tests.
 set(LIBC_GPU_LOADER_EXECUTABLE "" CACHE STRING "Executable for the GPU loader.")
 if(LIBC_GPU_LOADER_EXECUTABLE)