[NaCl SDK] Remove newlib toolchain from the SDK

native_client_sdk/src/examples/demo/earth/example.dsc

 {
-  'TOOLS': ['newlib', 'glibc', 'pnacl'],
+  'TOOLS': ['clang-newlib', 'glibc', 'pnacl'],
   'TARGETS': [
     {
       'NAME' : 'earth',
       'TYPE' : 'main',
       'SOURCES' : [
         'earth.cc'
       ],
      'LIBS': ['ppapi_simple_cpp', 'nacl_io', 'sdk_util', 'ppapi_cpp', 'ppapi', 'pthread']
     }
   ],
   'DATA': [
     'earth.jpg',
     'earthnight.jpg',
     'example.js',
   ],
   'DEST': 'examples/demo',
   'NAME': 'earth',
   'TITLE': 'Multi-Threaded Earth Demo',
   'GROUP': 'Demo'
 }