[libc][NFC] Add -Wno-multi-gpu everywhere for the GPU build (#83173)

Summary:
This warning is intended to indicate if `-march=native` returns
different values in a single compilation sense. As it stands we don't
care and it absolutely spams the test output if you run it on a machine
with more than one GPU like any cluster machine. Disable these warnings
everywhere we compile.

Author: jhuber6

libc/cmake/modules/LLVMLibCCompileOptionRules.cmake

@@ -87,6 +87,7 @@ function(_get_common_compile_options output_var flags)
     list(APPEND compile_options "-fvisibility=hidden")
     list(APPEND compile_options "-fconvergent-functions")
     list(APPEND compile_options "-flto")
+    list(APPEND compile_options "-Wno-multi-gpu")
 
     if(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
       list(APPEND compile_options "-Wno-unknown-cuda-version")

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -463,15 +463,15 @@ function(add_integration_test test_name)
 
   if(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
     target_link_options(${fq_build_target_name} PRIVATE
-      ${LIBC_COMPILE_OPTIONS_DEFAULT}
+      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
       -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto
       "-Wl,-mllvm,-amdgpu-lower-global-ctor-dtor=0" -nostdlib -static
       "-Wl,-mllvm,-amdhsa-code-object-version=${LIBC_GPU_CODE_OBJECT_VERSION}")
   elseif(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
     # We need to use the internal object versions for NVPTX.
     set(internal_suffix ".__internal__")
     target_link_options(${fq_build_target_name} PRIVATE
-      ${LIBC_COMPILE_OPTIONS_DEFAULT}
+      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
       "-Wl,--suppress-stack-size-warning"
       -march=${LIBC_GPU_TARGET_ARCHITECTURE} -nostdlib -static
       "--cuda-path=${LIBC_CUDA_ROOT}")
@@ -647,14 +647,14 @@ function(add_libc_hermetic_test test_name)
   if(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
     target_link_options(${fq_build_target_name} PRIVATE
       ${LIBC_COMPILE_OPTIONS_DEFAULT}
-      -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto
+      -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto -Wno-multi-gpu
       "-Wl,-mllvm,-amdgpu-lower-global-ctor-dtor=0" -nostdlib -static
       "-Wl,-mllvm,-amdhsa-code-object-version=${LIBC_GPU_CODE_OBJECT_VERSION}")
   elseif(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
     # We need to use the internal object versions for NVPTX.
     set(internal_suffix ".__internal__")
     target_link_options(${fq_build_target_name} PRIVATE
-      ${LIBC_COMPILE_OPTIONS_DEFAULT}
+      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
       "-Wl,--suppress-stack-size-warning"
       -march=${LIBC_GPU_TARGET_ARCHITECTURE} -nostdlib -static
       "--cuda-path=${LIBC_CUDA_ROOT}")