Add a new build target called "cmupdaterincremental".

This allows us to configure this in each device's BoardConfig:
```
TARGET_INCREMENTAL_OTA_VERBATIM_FILES := system/app/Provision.apk
```

It's required because that file is overwritten when installing incremental updates after gapps were installed.

All devices should use the Quarx2k/android_build fork instead of the CyanogenMod/android_build variant.