Organize BUCK for torch/standalone (#156503)

Summary: Undo highlevel BUCKification in favor of something more organized by moving it to the dir itself

Test Plan:
CI

Rollback Plan:

Reviewed By: swolchok

Differential Revision: D76920013

Pull Request resolved: https://github.com/pytorch/pytorch/pull/156503
Approved by: https://github.com/swolchok

BUILD.bazel

@@ -671,14 +671,6 @@ flatbuffer_cc_library(
     out_prefix = "torch/csrc/jit/serialization/",
 )
 
-cc_library(
-    name = "torch_standalone_headers",
-    hdrs = glob([
-        "torch/standalone/**/*.h"
-    ]),
-    visibility = ["//visibility:public"],
-)
-
 cc_library(
     name = "torch_headers",
     hdrs = if_cuda(

c10/core/build.bzl

@@ -80,7 +80,6 @@ def define_targets(rules):
         deps = [
             ":ScalarType",
             "//third_party/cpuinfo",
-            "//:torch_standalone_headers",
             "//c10/macros",
             "//c10/util:TypeCast",
             "//c10/util:base",

c10/macros/build.bzl

@@ -13,7 +13,7 @@ def define_targets(rules):
         local_defines = ["C10_BUILD_MAIN_LIB"],
         visibility = ["//visibility:public"],
         deps = [
-            "//:torch_standalone_headers",
+            "//torch/standalone:torch_standalone_headers",
         ],
     )
 

c10/ovrsource_defs.bzl

@@ -74,7 +74,7 @@ def define_c10_ovrsource(name, is_mobile):
             ],
         }),
         exported_deps = [
-            "//xplat/caffe2:torch_standalone_headers",
+            "//xplat/caffe2/torch/standalone:torch_standalone_headers",
             ":ovrsource_c10_cmake_macros.h",
             "//arvr/third-party/gflags:gflags",
             "//third-party/cpuinfo:cpuinfo",

c10/util/build.bzl

@@ -34,7 +34,7 @@ def define_targets(rules):
         visibility = ["//visibility:public"],
         deps = [
             ":bit_cast",
-            "//:torch_standalone_headers",
+            "//torch/standalone:torch_standalone_headers",
             "//c10/macros",
             "@fmt",
             "@moodycamel//:moodycamel",
@@ -92,7 +92,7 @@ def define_targets(rules):
             ],
         ),
         deps = [
-            "//:torch_standalone_headers",
+            "//torch/standalone:torch_standalone_headers",
         ],
         visibility = ["//visibility:public"],
     )

torch/standalone/BUILD.bazel

@@ -0,0 +1,9 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+cc_library(
+    name = "torch_standalone_headers",
+    hdrs = glob([
+        "**/*.h"
+    ]),
+    visibility = ["//visibility:public"],
+)