build: qcom: Set QCOM_*_PATH variables for hardware/qcom-* projects

This consolidates a bunch of one-off logic scattered throughout the
code base.  Usage in Android.mk files is trivial:

At top level, use e.g. "ifeq ($(call my-dir),$(QCOM_AUDIO_PATH))".
This works for all variants, including non-variants (i.e. AOSP).

Within subdirs, use e.g. hardware/qcom/audio => $(QCOM_AUDIO_PATH)

Change-Id: Iee2497ea9a7efeb4ae9e861b84c532b19da7b69d
Revert "Fixed mounting /system when 'override_prop' is enabled."

This reverts commit 2174d181daf62e6b9690436489506e7b0393b932.
repopick: allow specifying a topic to pick all commits from

Change-Id: I4fb60120794a77986bf641de063a8d41f4f45a23
Revert "CM/Build: f2fs support"

This reverts commit 515a5c21efeea2759ebb6b3b2ca158fb327d9548.
Merge pull request #2 from AOGP/kitkat

Kitkat