Add 'Linux LTO' buildbot (src part).

tools/mb/mb_config.pyl

 # 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.
 
 {
   # This is a map of buildbot master names -> buildbot builder names ->
   # config names (where each config name is a key in the 'configs' dict,
   # below). MB uses this dict to look up which config to use for a given bot.
   'masters': {
     # Take care when changing any of these builders to ensure that you do not
@@ skipping 188 matching lines @@
       'CrWinClngLLDdbg tester': 'none',
       'Headless Linux (dbg)':
         '//build/args/bots/chromium.fyi/headless_linux_dbg.gn',
       'MD Top Chrome ChromeOS material-hybrid':
         'gyp_chromeos_with_codecs_debug_bot',
       'MD Top Chrome ChromeOS non-material':
         'gyp_chromeos_with_codecs_debug_bot',
       'MD Top Chrome Win material':
         'gyp_debug_bot_minimal_symbols_x64',
       'MD Top Chrome Linux material': 'gn_debug_bot',
+      'LTO Linux': 'gn_official_goma_lto',
       'LTO Linux Perf': 'gn_official_goma_lto',
       'Libfuzzer Upload Linux ASan': 'gn_release_libfuzzer_asan',
       'Libfuzzer Upload Linux ASan Debug': 'gn_debug_libfuzzer_asan',
       'Libfuzzer Upload Linux MSan': 'gn_release_libfuzzer_msan',
       'Libfuzzer Upload Linux UBSan': 'gn_release_libfuzzer_ubsan',
       'Linux ARM': 'swarming_gn_release_bot_arm',
       'Linux Kitchen (kitchen_run)': 'swarming_gn_release_bot',
       'Linux Kitchen (annotated_run)': 'swarming_gn_release_bot',
       'Linux V8 API Stability': 'gn_release_bot',
       'Site Isolation Linux': 'gn_release_trybot',
@@ skipping 2086 matching lines @@
     },
 
     'drfuzz': { 'gn_args': 'use_drfuzz=true' },
 
     'drmemory': {
       'gn_args': 'is_component_build=true enable_iterator_debugging=false',
       'gyp_defines': 'component=shared_library build_for_tool=drmemory',
     },
   },
 }