Delete shared/platform/osx/strnlen_osx.c.

src/shared/platform/BUILD.gn

 # Copyright (c) 2014 The Native ClientAuthors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 #  Autogenerated from src/shared/platform/build.scons.
 
 static_library("platform") {
   if (current_os == "nacl") {
     sources = [
       "nacl_check.c",
@@ skipping 63 matching lines @@
         "win/port_win.c",
         "win/xlate_system_error.c",
       ]
     }
 
     if (current_os == "mac") {
       sources += [
         "osx/nacl_clock.c",
         "osx/nacl_host_dir.c",
         "osx/nacl_semaphore.c",
-        "osx/strnlen_osx.c",
       ]
     }
 
     if (is_linux) {
       sources += [
         "linux/nacl_clock.c",
         "linux/nacl_host_dir.c",
         "linux/nacl_semaphore.c",
       ]
     }
 
     if (current_os == "win") {
       cflags_c = [
         "/DUNICODE",
         "/D_CRT_RAND_S",
         "/D_UNICODE",
       ]
     }
   }
   deps = [
     "//build/config/nacl:nacl_base",
     "//native_client/src/shared/gio:gio",
   ]
 }