[libc] Switch to using the generic <gpuintrin.h> implementations (#121810)

Summary:
This patch switches the GPU utility helpers to wrapping around the
gpuintrin.h ones with a C++ flavor.

Author: jhuber6

libc/src/__support/GPU/CMakeLists.txt

@@ -1,16 +1,12 @@
-if(NOT EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
+# These utilities are GPU only.
+if(NOT LIBC_TARGET_OS_IS_GPU)
   return()
 endif()
 
-add_subdirectory(${LIBC_TARGET_ARCHITECTURE})
-set(target_gpu_utils libc.src.__support.GPU.${LIBC_TARGET_ARCHITECTURE}.${LIBC_TARGET_ARCHITECTURE}_utils)
-
 add_header_library(
   utils
   HDRS
     utils.h
-  DEPENDS
-    ${target_gpu_utils}
 )
 
 add_object_library(
@@ -21,6 +17,6 @@ add_object_library(
     allocator.h
   DEPENDS
     libc.src.__support.common
-    libc.src.__support.GPU.utils
     libc.src.__support.RPC.rpc_client
+    .utils
 )