add support unicode font not only ascii

  need to define custom theme(include custom ttf files)
  in device tree :

  TW_CUSTOM_THEME := device/xxxx/yyyy/recovery/res

  For example:
  https://github.com/twrp/android_device_xiaomi_armani

Change-Id: I6bebdfbdd75c99bfe216a8c0789af63c6fe4b9de