Update on "Reuse GELU implementation from PyTorch core"

kernels/optimized doesn't need to support embedded systems, so it can just take a header-only dep on PyTorch.

Note that, because we will pick up Sleef internally and ignore it
externally thanks to ATen vec, this PR gets to enable optimized GELU in OSS.

Testing: CI to make sure this doesn't break mobile build modes; happy to take advice on anything not currently covered that might break.

Differential Revision: [D66335522](https://our.internmc.facebook.com/intern/diff/D66335522/)

[ghstack-poisoned]

Author: swolchok

runtime/core/portable_type/c10/targets.bzl

@@ -67,7 +67,7 @@ def define_common_targets():
             # fbsource//third-party/sleef:sleef currently fails to
             # link with missing symbols, hence the fbcode-specific dep below.
         }),
-        fbcode_exported_deps = [
+        fbcode_exported_deps = ([
             "//caffe2:aten-headers-cpu",
             "//caffe2:generated-config-header",
             "//caffe2/c10/core:base_headers",
@@ -76,7 +76,7 @@ def define_common_targets():
             "ovr_config//cpu:x86_64": [
                 "third-party//sleef:sleef",
             ]
-        }),
+        })) if not runtime.is_oss else [],
         fbcode_exported_preprocessor_flags = [
             # We don't -DCPU_CAPABILITY=AVX2 because that trips
             # -Wmacro-redefined, and we only care about getting

shim/xplat/executorch/build/env_interface.bzl

@@ -119,7 +119,7 @@ def _remove_platform_specific_args(kwargs):
     keys = []
     for key in kwargs:
         if (key.endswith("_platform_preprocessor_flags") or key.endswith("_platform_deps") or
-            key.startswith("fbobjc") or key.endswith("_platform_compiler_flags")):
+            key.startswith("fbobjc") or key.endswith("_platform_compiler_flags") or key == "fbcode_exported_preprocessor_flags"):
             keys.append(key)
     for key in keys:
         kwargs.pop(key)