gn: use bundled binutils via -B

tools/gn/bin/gyp_flag_compare.py

 #!/usr/bin/env python
 
 # Copyright 2014 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.
 
 """Given the output of -t commands from a ninja build for a gyp and GN generated
 build, report on differences between the command lines."""
 
 
@@ skipping 95 matching lines @@
     # Filter for libFindBadConstructs.so having a relative path in one and
     # absolute path in the other.
     others_filtered = []
     for x in others:
       if x.startswith('-Xclang ') and x.endswith('libFindBadConstructs.so'):
         others_filtered.append(
             '-Xclang ' +
             os.path.join(os.getcwd(),
                          os.path.normpath(
                              os.path.join('out/gn_flags', x.split(' ', 1)[1]))))
+      elif x.startswith('-B'):
+        others_filtered.append(
+            '-B' +
+            os.path.join(os.getcwd(),
+                         os.path.normpath(os.path.join('out/gn_flags', x[2:]))))
       else:
         others_filtered.append(x)
     others = others_filtered
 
     flags_by_output[cc_file[0]] = {
       'output': output_name,
       'depname': dep_name,
       'defines': sorted(defines),
       'include_dirs': sorted(include_dirs),  # TODO(scottmg): This is wrong.
       'dash_f': sorted(dash_f),
@@ skipping 87 matching lines @@
     print '\n'.join(sorted(files))
     print diff
 
   print 'Total differences:', g_total_differences
   # TODO(scottmg): Return failure on difference once we're closer to identical.
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())