[libc] Can build amdgpu libc even if rocm is missing

Clang defaults to failing to build if it can't find rocm device libs

Reviewed By: jhuber6

Differential Revision: https://reviews.llvm.org/D153581

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -520,12 +520,12 @@ function(add_integration_test test_name)
   # The GPU build requires overriding the default CMake triple and architecture.
   if(LIBC_GPU_TARGET_ARCHITECTURE_IS_AMDGPU)
     target_compile_options(${fq_build_target_name} PRIVATE
-                           -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE}
+                           -nogpulib -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE}
                            -flto --target=${LIBC_GPU_TARGET_TRIPLE})
   elseif(LIBC_GPU_TARGET_ARCHITECTURE_IS_NVPTX)
     get_nvptx_compile_options(nvptx_options ${LIBC_GPU_TARGET_ARCHITECTURE})
     target_compile_options(${fq_build_target_name} PRIVATE
-                           ${nvptx_options} -fno-use-cxa-atexit
+                           -nogpulib ${nvptx_options} -fno-use-cxa-atexit
                            --target=${LIBC_GPU_TARGET_TRIPLE})
   endif()
 
@@ -571,11 +571,11 @@ set(LIBC_HERMETIC_TEST_COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_DEFAULT}
 # The GPU build requires overriding the default CMake triple and architecture.
 if(LIBC_GPU_TARGET_ARCHITECTURE_IS_AMDGPU)
   list(APPEND LIBC_HERMETIC_TEST_COMPILE_OPTIONS
-       -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto --target=${LIBC_GPU_TARGET_TRIPLE})
+       -nogpulib -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto --target=${LIBC_GPU_TARGET_TRIPLE})
 elseif(LIBC_GPU_TARGET_ARCHITECTURE_IS_NVPTX)
   get_nvptx_compile_options(nvptx_options ${LIBC_GPU_TARGET_ARCHITECTURE})
   list(APPEND LIBC_HERMETIC_TEST_COMPILE_OPTIONS
-       ${nvptx_options} -fno-use-cxa-atexit --target=${LIBC_GPU_TARGET_TRIPLE})
+       -nogpulib ${nvptx_options} -fno-use-cxa-atexit --target=${LIBC_GPU_TARGET_TRIPLE})
 endif()
 
 # Rule to add a hermetic test. A hermetic test is one whose executable is fully