NaCl: Fix irt_shim_ppapi.c to compile with -Wstrict-prototypes

ppapi/native_client/src/untrusted/pnacl_irt_shim/irt_shim_ppapi.c

 /*
  * 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.
  */
 
 #include "ppapi/native_client/src/untrusted/pnacl_irt_shim/irt_shim_ppapi.h"
 
 #include "native_client/src/untrusted/irt/irt.h"
 #include "ppapi/nacl_irt/public/irt_ppapi.h"
@@ skipping 15 matching lines @@
 
 static int32_t shim_PPPInitializeModule(PP_Module module_id,
                                         PPB_GetInterface get_browser_intf) {
   /* Record the original PPB_GetInterface and provide a shimmed one. */
   __set_real_Pnacl_PPBGetInterface(get_browser_intf);
   return (*g_user_start_functions.PPP_InitializeModule)(
       module_id,
       &__Pnacl_PPBGetInterface);
 }
 
-static void shim_PPPShutdownModule() {
+static void shim_PPPShutdownModule(void) {
   (*g_user_start_functions.PPP_ShutdownModule)();
 }
 
 #ifdef PNACL_SHIM_AOT
  /*
   * This will be discovered and set by the shim, since we cannot link
   * against the IRT directly in the AOT library.
   */
 int (*real_irt_ppapi_start)(const struct PP_StartFunctions *) = NULL;
 #else
@@ skipping 23 matching lines @@
    */
   return (*real_irt_ppapi_start)(&wrapped_ppapi_methods);
 }
 
 #ifndef PNACL_SHIM_AOT
 const struct nacl_irt_ppapihook nacl_irt_ppapihook_pnacl_private = {
   irt_shim_ppapi_start,
   PpapiPluginRegisterThreadCreator,
 };
 #endif