Add comment to PPB_MouseInputEvent version 1.1 that GetMovement hasn't been supported.

ppapi/ppapi_cpp.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'ppapi_c<(nacl_ppapi_library_suffix)',
       'type': 'none',
       'all_dependent_settings': {
@@ skipping 48 matching lines @@
         'c/dev/ppb_context_3d_trusted_dev.h',
         'c/dev/ppb_console_dev.h',
         'c/dev/ppb_cursor_control_dev.h',
         'c/dev/ppb_directory_reader_dev.h',
         'c/dev/ppb_file_chooser_dev.h',
         'c/dev/ppb_find_dev.h',
         'c/dev/ppb_font_dev.h',
         'c/dev/ppb_fullscreen_dev.h',
         'c/dev/ppb_graphics_3d_dev.h',
         'c/dev/ppb_graphics_3d_trusted_dev.h',
+        'c/dev/ppb_input_event_dev.h',
         'c/dev/ppb_memory_dev.h',
         'c/dev/ppb_opengles_dev.h',
         'c/dev/ppb_query_policy_dev.h',
         'c/dev/ppb_scrollbar_dev.h',
         'c/dev/ppb_surface_3d_dev.h',
         'c/dev/ppb_testing_dev.h',
         'c/dev/ppb_url_util_dev.h',
         'c/dev/ppb_video_decoder_dev.h',
         'c/dev/ppb_widget_dev.h',
         'c/dev/ppb_zoom_dev.h',
@@ skipping 203 matching lines @@
         }],
         ['OS=="mac"', {
           'xcode_settings': {
             'WARNING_CFLAGS': ['-Wextra', '-pedantic'],
            },
         }]
       ],
     },
   ],
 }