Custom build systems definitions to add PRODUCT_PACKAGES filtering
without having to define a completely new product_config or create
unnecessary forks of upstream repos

Example :

Remove OpenWnn and associated libs by appending the following
the end of a device mk file , e.g device/archos/a80sboard/full_a80sboard.mk

PRODUCT_PACKAGES_FILTER := \
        OpenWnn \
        PinyinIME \
        libWnnEngDic \
        libWnnJpnDic \
        libwnndict \