Build - Add support for PRODUCT_COPY_FILES_OVERRIDES

* We may have a case where prebuilts need to be built from
   source instead based on an externalized config.
* New directive takes a list of destination files to remove from
   PRODUCT_COPY_FILES so that other instructions can be supplied.

Change-Id: I87a66600e2fd41b95759ad0f04e657e4979250c2
Signed-off-by: STELIX <ssspinni@gmail.com>
Build - Add QCOM target-specific config

* Needed to support global DirectTract config on legacy targets
* Let's also eliminate some boilerplate

Change-Id: I22aea62e07a26fa99ab82152a8f0a9b12d27e683
Signed-off-by: STELIX <ssspinni@gmail.com>