Add support of x64 to generate .mk files

android_webview/tools/gyp_webview

 #!/bin/bash
 
 # Copyright (c) 2012 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.
 
 # This script runs gyp with the configuration required to build WebView in the
 # Android build system. It is not necessary to source build/android/envsetup.sh
 # before running this script.
 
@@ skipping 50 matching lines @@
       '${ANDROID_BUILD_TOP}')")
   EFLAGS=\
 "${FLAGS} -Dhost_os=${host_os} -Dandroid_sdk_tools=\$(PWD)/${android_sdk_tools}"
 
   if [ "$PLATFORM" == "${host_platform}-arm" -o "$PLATFORM" == "all" ]; then
     ${GYP} --suffix .${host_platform}-arm ${EFLAGS} -Dtarget_arch=arm
   fi
   if [ "$PLATFORM" == "${host_platform}-x86" -o "$PLATFORM" == "all" ]; then
     ${GYP} --suffix .${host_platform}-x86 ${EFLAGS} -Dtarget_arch=ia32
   fi
+  if [ "$PLATFORM" == "${host_platform}-x86_64" -o "$PLATFORM" == "all" ]; then
+    ${GYP} --suffix .${host_platform}-x86_64 ${EFLAGS} -Dtarget_arch=x64
+  fi
   if [ "$PLATFORM" == "${host_platform}-mips" -o "$PLATFORM" == "all" ]; then
     ${GYP} --suffix .${host_platform}-mips ${EFLAGS} -Dtarget_arch=mipsel
   fi
 done