Minimal reproduction for SEGFAULT with -Wl,--as-needed -pthread -O2.

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 704 matching lines @@
       "//chrome/browser/resources:extension_resource_demo",
       "//chrome/installer/util:strings",
       "//chrome/tools/convert_dict",
       "//components/constrained_window:unit_tests",
       "//components/filesystem:filesystem_service_unittests",
       "//components/leveldb:leveldb_service_unittests",
       "//components/metrics:serialization",
       "//components/password_manager/content/renderer:browser_tests",
       "//components/rappor:unit_tests",
       "//components/sessions:unit_tests",
+      "//flto_repro",
       "//media/blink:media_blink_unittests",
       "//media/cast:udp_proxy",
       "//native_client/src/trusted/debug_stub:gdb_rsp_unittest",
       "//storage/browser:dump_file_system",
       "//third_party/angle:libANGLE",
       "//third_party/angle:libEGL",
       "//third_party/angle:libGLESv2",
       "//third_party/leveldatabase:leveldb_arena_test",
       "//third_party/leveldatabase:leveldb_bloom_test",
       "//third_party/leveldatabase:leveldb_cache_test",
@@ skipping 298 matching lines @@
   assert(target_name != "")  # Mark as used.
   sources = invoker.actual_sources
   assert(
       sources == invoker.actual_sources,
       "Do not use a platform name in your output directory (found \"$root_build_dir\"). http://crbug.com/548283")
 }
 
 assert_valid_out_dir("_unused") {
   actual_sources = [ "$root_build_dir/foo" ]
 }