Turn off LTO again for Official Win/Clang LLD builds

build/config/compiler/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.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 1472 matching lines @@
         if (!is_clang) {
           cflags += [
             "/GL",  # Whole program optimization.
 
             # Disable Warning 4702 ("Unreachable code") for the WPO/PGO builds.
             # Probably anything that this would catch that wouldn't be caught
             # in a normal build isn't going to actually be a bug, so the
             # incremental value of C4702 for PGO builds is likely very small.
             "/wd4702",
           ]
-        } else if (is_clang && use_lld) {
-          cflags += [ "-flto" ]  # Link-time optimization (whole program optimization).
         }
+        # TODO(crbug.com/598772): Enable -flto for Clang.
       }
     } else if (optimize_for_fuzzing) {
       cflags = [ "-O1" ] + common_optimize_on_cflags
     } else {
       cflags = [ "-O2" ] + common_optimize_on_cflags
     }
   }
 }
 
 # This config can be used to override the default settings for per-component
@@ skipping 189 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }