Use xplat/caffe2:ovrsource_aten_Config.h for arvr build modes (#9462)

Summary:

For arvr modes we should use `//xplat/caffe2:ovrsource_aten_Config.h` to get the ATen config headers as the `ovrsource` variants are what's used in arvr repos and using ``"//xplat/caffe2:ovrsource_aten_Config.h"` causes the ovrsource ones to get overwritten and hence results in build failures.

Reviewed By: thejarlid

Differential Revision: D71506180

Author: tarun292

runtime/core/portable_type/c10/c10/targets.bzl

@@ -1,4 +1,5 @@
 load("@fbsource//xplat/executorch/build:runtime_wrapper.bzl", "runtime")
+load("@fbsource//tools/build_defs:fbsource_utils.bzl", "is_arvr_mode")
 
 def get_sleef_preprocessor_flags():
     if runtime.is_oss:
@@ -78,9 +79,8 @@ def define_common_targets():
         ] + get_sleef_preprocessor_flags(),
         xplat_exported_deps = [
             "//xplat/caffe2:aten_header",
-            "//xplat/caffe2:generated_aten_config_header",
             "//xplat/caffe2/c10:c10_headers",
-        ],
+        ] + ["//xplat/caffe2:ovrsource_aten_Config.h" if is_arvr_mode() else "//xplat/caffe2:generated_aten_config_header",],
         exported_preprocessor_flags = select({
             # Intentionally punting on non-fbcode x86 sleef support
             # for now because of fbsource//third-party/sleef:sleef