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
(((AOSPAL OPTIMIZATION)))

Change-Id: I3e79993c44f249b6a15f4f25e1e39057582b21c5
Add -mfpu=neon-fp16 to unknown Clang flags.
Add (some) support for TARGET_FPU_VARIANT.

Change-Id: I7a08346142a054ac106f326233af97f25f2acf50
Add Linker Optimizations

* Make these optional as well as the Clang optimizations.
* Enable using OPTIMIZE_LINKER=y to BoardConfig of your device.

CREDIT Chet Kener

Change-Id: Ie52c175bde325060216e4085582ec0d0534d30fd
set back default GCC SaberMod 4.8

Change-Id: I57aa36856251ae07ba431e0afce885d4dfb55b67
Revert "Add Linker Optimizations"

This reverts commit 9e3dfc162db2bfd3dfd09e42892f6813d251ea21.
Rom Optimized by zion959

Change-Id: Iade90f01288c83cc15073b2f865303e5ddd835d8
Add Linker Optimizations

* Make these optional as well as the Clang optimizations.
* Enable using OPTIMIZE_LINKER=y to BoardConfig of your device.

CREDIT Chet Kener

Change-Id: Ie52c175bde325060216e4085582ec0d0534d30fd