Fix SLEEF preprocessor macro name to match ATen vec headers

Differential Revision: D118475079

Pull Request resolved: pytorch#22442

Author: JakeStevens

kernels/optimized/lib_defs.bzl

@@ -25,16 +25,16 @@ def get_vec_preprocessor_flags():
         # various ovr_configs are not available in oss
         preprocessor_flags = select({
             "ovr_config//os:linux-x86_64": [
-                "-DET_BUILD_ARM_VEC256_WITH_SLEEF",
+                "-DAT_BUILD_ARM_VEC256_WITH_SLEEF",
             ] if not runtime.is_oss else [],
             "ovr_config//os:iphoneos-arm64": [
-                "-DET_BUILD_ARM_VEC256_WITH_SLEEF",
+                "-DAT_BUILD_ARM_VEC256_WITH_SLEEF",
             ] if not runtime.is_oss else [],
             "ovr_config//os:macos-arm64": [
-                "-DET_BUILD_ARM_VEC256_WITH_SLEEF",
+                "-DAT_BUILD_ARM_VEC256_WITH_SLEEF",
             ] if not runtime.is_oss else [],
             "ovr_config//os:android-arm64": [
-                "-DET_BUILD_ARM_VEC256_WITH_SLEEF",
+                "-DAT_BUILD_ARM_VEC256_WITH_SLEEF",
             ] if not runtime.is_oss else [],
             "DEFAULT": [],
         })