build: use the system's ccache by default

ccache 3.x supports direct mode (http://ccache.samba.org/manual.html#_the_direct_mode)
This is not supported in the prebuilt version. Direct mode has been shown to decrease build time by up to 40x, compared to preprocessor mode used in ccache 2.4, which is substantially less

Change-Id: I224de8e5bc53bbe18a7a02fc811324307cf3ab8c
Allow devices to specify certain ro. props via TARGET_UNIFIED_DEVICE

This modifies buildinfo.sh to not set model, name, description, and
fingerprint in build.prop. These can then be set via custom init
lib.
This also fixes ota_from_target_files to function without these
props being preset.

Change-Id: I945b2c38e60b207d2d0f82b34f4f230ac21b0657
Delete unsupported Prop

unified devices not support

ro.product.device
ro.product.model

PS1: switch to ro.cm.device

Change-Id: I14a280c6173af4efb627faf622acf583a158b40d
Signed-off-by: SectorAndroidRD <SectorAndroidRD@gmail.com>
Update BUILD_ID to KVT49L

Change-Id: Ia9f1808d18f0359d9c161324fd336cb364cd8af8
Merge remote-tracking branch 'PAC-man/pac-4.4' into pac-4.4
[HAX] Allow per-target dtbTool

 * Revert this when fixed

Change-Id: I97ecb0448ae7bd5859454be290c5dde6248b2859
Merge remote-tracking branch 'PAC-man/pac-4.4' into pac-4.4