[gn build] Port af5abd9

Author: llvmgnsyncbot

llvm/utils/gn/secondary/clang/lib/Headers/BUILD.gn

@@ -223,6 +223,7 @@ copy("Headers") {
     "hlsl.h",
     "hlsl/hlsl_alias_intrinsics.h",
     "hlsl/hlsl_basic_types.h",
+    "hlsl/hlsl_compat_overloads.h",
     "hlsl/hlsl_detail.h",
     "hlsl/hlsl_intrinsic_helpers.h",
     "hlsl/hlsl_intrinsics.h",