Delete empty mojo python package, and prefix all python packages with mojo_

mojo/python/system/mojo_embedder.pyx

 # 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.
 
 # distutils: language = c++
 
 from libc.stdint cimport uintptr_t
 from libcpp cimport bool
 
-from mojo import system
-from mojo import system_impl
+import mojo_system
+import mojo_system_impl
 
 cdef extern from "third_party/cython/python_export.h":
   pass
 
 cdef extern from "base/memory/scoped_ptr.h":
   cdef cppclass scoped_ptr[T]:
     scoped_ptr(T*)
 
 cdef extern from "mojo/edk/embedder/platform_support.h" \
     namespace "mojo::embedder" nogil:
@@ skipping 14 matching lines @@
     pass
   cdef MojoSystemThunks MojoMakeSystemThunks()
 
 cdef extern from "mojo/edk/embedder/test_embedder.h" nogil:
   cdef bool ShutdownCEmbedderForTest "mojo::embedder::test::Shutdown"()
 
 def Init():
   InitCEmbedder(scoped_ptr[PlatformSupport](
       new SimplePlatformSupport()))
   cdef MojoSystemThunks thunks = MojoMakeSystemThunks()
-  system.SetSystemThunks(<uintptr_t>(&thunks))
-  system_impl.SetSystemThunks(<uintptr_t>(&thunks))
+  mojo_system.SetSystemThunks(<uintptr_t>(&thunks))
+  mojo_system_impl.SetSystemThunks(<uintptr_t>(&thunks))
 
 def ShutdownForTest():
   return ShutdownCEmbedderForTest()