core: main: remove all the spam about including make files

Change-Id: Ifd2ef0e239d16b169c572472416c2c31df62a367
Allow Device Specific Headers

This allows a device to define its own headers compared to default

Conflicts:
	core/binary.mk
Allow a device to generically define its own headers

We have a few cases of devices including specific versions of projects
just because of modified headers (msm_mdp.h comes to mind), and I just
had enough of ifdeffing header files for specific cases (the P990 needs
a lot of these).
Now... if a target defines a TARGET_SPECIFIC_HEADER_PATH, any headers in
there will take precedence over the standard ones; for example, on the
p990, I have

TARGET_SPECIFIC_HEADER_PATH := device/lge/p990/include

which makes, for example, the
device/lge/p990/include/hardware_legacy/AudioHardwareInterface.h be
used instead of
hardware/libhardware_legacy/include/hardware_legacy/AudioHardwareInterface.h
whenever a source file uses <hardware_legacy/AudioHardwareInterface.h>

Change-Id: I41b62668b60e3f62a6ebd3738d8d2675103a81e6a

build: fix target header overlay

LOCAL_C_INCLUDES as defined by the makefile should be put AFTER
the overlay includes so the overlay always takes precedence.

Change-Id: I489b2aab6dbacd9122d834f85e07b63ed1271f07
Make the kernel image format parametric instead of a chain of if/elses

Change-Id: I54bfcdecb8647f7bcf744e72b2de19fcf4e4e7ac

Conflicts:
	core/tasks/kernel.mk