build: Remove build system support for gold plugin.

chrome/test/data/nacl/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/toolchain.gni")
 import("//ppapi/native_client/nacl_test_data.gni")
 
 group("nacl") {
@@ skipping 547 matching lines @@
     # Workaround against LLVM bug.
     # In short, an LTO optimization pass might recognize
     # naive implementations of builtins (such as memset)
     # and replace them with references to the real builtins,
     # which, in the case of -nostdlib, might cause the binary
     # to get undefined references to those symbols.
     #
     # See more details:
     # https://llvm.org/bugs/show_bug.cgi?id=30403
     if (use_thin_lto) {
-      if (use_lld) {
-        ldflags = [ "-Wl,--lto-O0" ]
-      } else {
-        ldflags = [ "-Wl,-plugin-opt,O0" ]
-      }
+      ldflags = [ "-Wl,--lto-O0" ]
     }
   }
 
   executable("nonsfi_libc_free_nexe") {
     output_name = "libc_free_$arch"
     output_extension = "nexe"
     sources = [
       "nonsfi/libc_free.c",
     ]
 
@@ skipping 40 matching lines @@
       "nonsfi/libc_free.nmf",
     ]
     outputs = [
       "${root_build_dir}/nacl_test_data/libc-free/{{source_file_part}}",
     ]
     deps = [
       ":nonsfi_libc_free_nexe",
     ]
   }
 }