Remove few more errors in mac scons build.

skia/SConscript

 # Copyright (c) 2006-2008 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('env')
 
 env = env.Clone()
 
 env.Prepend(
   CPPPATH = [
@@ skipping 19 matching lines @@
 
       '/wd4244',
       '/wd4267',
       '/wd4345',
       '/wd4390',
       '/wd4554',
       '/wd4800',
     ],
   )
 elif env['PLATFORM'] in ('posix', 'darwin'):
-  # Because images/SkStream.cpp has len asserts.
-  env.Append(CCFLAGS = ['-Wno-unused-variable'])
+  env.Append(CCFLAGS = ['-Wno-unused'])
 
 input_files = [
   'animator/SkTime.cpp',
   'corecg/Sk64.cpp',
   'corecg/SkBuffer.cpp',
   'corecg/SkChunkAlloc.cpp',
   'corecg/SkCordic.cpp',
   'corecg/SkDebug.cpp',
   'corecg/SkDebug_stdio.cpp',
   'corecg/SkFloat.cpp',
@@ skipping 153 matching lines @@
   # in the skia directory.
   # TODO(bradnelson): This step creates a skia.pch.ib_tag file to be created. 
   # It's a 0-length file so likely harmless.  Is this a side effect of having
   # IncrediBuild installed on the build machine?
   pch, obj = env_p.PCH(['skia.pch', 'precompiled.obj'], 'precompiled.cc')
   env_p['PCH'] = pch
   input_files += [obj]
 
 env.ChromeStaticLibrary('skia', input_files)