[NaCl SDK] Make the SDK examples buildable as a packaged app.

native_client_sdk/src/examples/hello_world_instance3d/example.dsc

 {
   'TOOLS': ['newlib', 'glibc', 'pnacl'],
   'TARGETS': [
     {
       'NAME' : 'hello_world_instance3d',
       'TYPE' : 'main',
       'SOURCES' : ['hello_world.cc', 'matrix.cc', 'matrix.h'],
       'CXXFLAGS': [
         '-I../../src',
         '-I../../src/ppapi/lib/gl'
       ],
       'LIBS': ['ppapi_main', 'nacl_io', 'ppapi_gles2', 'ppapi_cpp', 'ppapi',
                'pthread']
     }
   ],
   'DATA': [
     'fragment_shader_es2.frag',
     'hello.raw',
     'vertex_shader_es2.vert'
   ],
   'DEST': 'examples',
   'NAME': 'hello_world_instance3d',
   'TITLE': 'Hello World GLES 2.0 using ppapi_instance3d',
-  'DESC': """
-The Hello World GLES 2.0 example demonstrates how to create a 3D cube
-that rotates.  This is a simpler example than the tumbler example, and
-written in C.  It loads the assets using URLLoader.""",
-  'FOCUS': '3D graphics, URL Loader.',
   'GROUP': 'API'
 }