Make which gold and binutils used configurable.

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")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
@@ skipping 12 matching lines @@
 declare_args() {
   # Normally, Android builds are lightly optimized, even for debug builds, to
   # keep binary size down. Setting this flag to true disables such optimization
   android_full_debug = false
 
   # Whether to use the binary binutils checked into third_party/binutils.
   # These are not multi-arch so cannot be used except on x86 and x86-64 (the
   # only two architectures that are currently checked in). Turn this off when
   # you are using a custom toolchain and need to control -B in cflags.
   linux_use_bundled_binutils = is_linux && current_cpu == "x64"
+  binutils_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
+                              root_build_dir)
 
   # Compile in such a way as to enable profiling of the generated code. For
   # example, don't omit the frame pointer and leave in symbols.
   enable_profiling = false
 
   # Compile in such a way as to make it possible for the profiler to unwind full
   # stack frames. Setting this flag has a large effect on the performance of the
   # generated code than just setting profiling, but gives the profiler more
   # information to analyze.
   # Requires profiling to be set to true.
   enable_full_stack_frames_for_profiling = false
 
   # Use gold for linking on 64-bit Linux only (on 32-bit it runs out of
   # address space, and it doesn't support cross-compiling).
   use_gold = is_linux && current_cpu == "x64"
 
+  # When we are going to use gold we need to find it.
+  if (use_gold) {
+    gold_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
+                            root_build_dir)
+  } else {
+    gold_path = ""
+  }
+
   # use_debug_fission: whether to use split DWARF debug info
   # files. This can reduce link time significantly, but is incompatible
   # with some utilities such as icecc and ccache. Requires gold and
   # gcc >= 4.8 or clang.
   # http://gcc.gnu.org/wiki/DebugFission
   use_debug_fission = is_debug && !is_win && use_gold &&
                       linux_use_bundled_binutils && !use_ccache
 
   if (is_win) {
     # Whether the VS xtree header has been patched to disable warning 4702. If
@@ skipping 390 matching lines @@
     }
   }
 
   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_linux) {
     cflags += [ "-pthread" ]
     ldflags += [ "-pthread" ]
   }
   if (use_gold) {
-    gold_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
-                            root_build_dir)
     ldflags += [
       "-B$gold_path",
 
       # Newer gccs and clangs support -fuse-ld, use the flag to force gold
       # selection.
       # gcc -- http://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Optimize-Options.html
       "-fuse-ld=gold",
 
       # Experimentation found that using four linking threads
       # saved ~20% of link time.
@@ skipping 13 matching lines @@
 
     # TODO(thestig): Make this flag work with GN.
     #if (!is_official_build && !is_chromeos && !(is_asan || is_lsan || is_tsan || is_msan)) {
     #  ldflags += [
     #    "-Wl,--detect-odr-violations",
     #  ]
     #}
   }
 
   if (linux_use_bundled_binutils) {
-    binutils_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
-                                root_build_dir)
     cflags += [ "-B$binutils_path" ]
   }
 
   # Clang-specific compiler flags setup.
   # ------------------------------------
   if (is_clang) {
     cflags += [ "-fcolor-diagnostics" ]
   }
 
   # C++11 compiler flags setup.
@@ skipping 775 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }