build: Add QCOM target-specific config

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

Change-Id: I736c10a5e7e1f3d1e0de9e60f29b60add276f151

Conflicts:
	core/config.mk

	modified:   core/config.mk
	new file:   core/qcom_target.mk