Don't list platform-posix.cc twice on android

BUILD.gn

 # 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.
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
 v8_compress_startup_data = "off"
 v8_deprecation_warnings = false
 v8_enable_disassembler = false
 v8_enable_gdbjit = false
@@ skipping 968 matching lines @@
     sources += [
       "src/platform-linux.cc"
     ]
 
     libs = [ "rt" ]
     if (v8_compress_startup_data == "bz2") {
       libs += [ "bz2" ]
     }
   } else if (is_android) {
     defines += [ "CAN_USE_VFP_INSTRUCTIONS" ]
-    sources += [ "src/platform-posix.cc" ]
 
     if (build_os == "mac") {
       if (current_toolchain == host_toolchain) {
         sources += [ "src/platform-macos.cc" ]
       } else {
         sources += [ "src/platform-linux.cc" ]
       }
     } else {
       sources += [ "src/platform-linux.cc" ]
       if (current_toolchain == host_toolchain) {
@@ skipping 152 matching lines @@
     deps = [
       ":v8_base",
       ":v8_nosnapshot",
     ]
   }
 
   direct_dependent_configs = [ ":external_config" ]
 }
 
 }