build: Add chromium prebuilt support to envsetup.sh && The core Makefile

This adds a chromium_prebuilt function to envsetup.sh that is invoked by lunch to check
whether the chromium prebuilts are up-to-date or not. If not, it will be built from source
and then the new source built version will be pulled during brunch/mka bacon to become the
new prebuilts for future builds.

This is all opt-in through the USE_PREBUILT_CHROMIUM flag. Without it being set to 1,
none of this would be ran, and regular operations will go on.

PS13:
-use export TARGET_DEVICE
-replace git -C with params compatible to old git versions

Change-Id: I40f8c8dbd2a8a84a5c1b9f47ee04180a71ef4e07
Prebuilt chromium: Run a check for target device directory

this should fix the issue that arises if device fails and device is built again, chromium will error out because it thinks the prebuilt files exist (which they are not, directories are just created).

Signed-off-by: Ayysir <ayysir@aospal.com>
Change-Id: I595cab268e66c738ccae9900150b36d7f9626a6e
Fix compatibility with zsh on finding device and vendor files for "including" and Execute the contents of any vendorsetup.sh files we can find. 
code re-used from paranoid.

Change-Id: I0c28bfacd90789fbcd7f7438cd35d828770f757d
Edify: Add AssertSomeBaseband

Allow releasetools.py to assert a baseband version. Works just like
AssertSomeBootloader.

Change-Id: Ic8eb341cef1d777d983be25ba21a3bc545819c29
Merge "Fix compatibility with zsh on finding device and vendor files for "including" and Execute the contents of any vendorsetup.sh files we can find.  code re-used from paranoid." into pac-4.4
ota_from_target_files: Validate signatures after possible data wipe

If the data is being wiped, we want to validate the signature after
this step. This is also a good check that the data wipe succeeded.

Change-Id: Iaecfddfb2010944de0c97e7bb21d8e581f20deec
Merge remote-tracking branch 'pac/pac-4.4' into pac-4.4