Write ro.build.ab_update to /vendor/build.prop.

It's a vendor-specific property, which was historically included into
/system/build.prop prior to this change.

Whether a target uses A/B OTA shouldn't affect anything on the system
image, including the `ro.build_ab_update` property. Moving it to vendor
partition will also make it consistent with other A/B specific configs,
such as the `slotselect` flag in device fstab
(/vendor/etc/fstab.$(PRODUCT_PLATFORM)).

Bug: 130516531
Test: Build and flash crosshatch-userdebug. Check /system/build.prop,
      /vendor/build.prop and the runtime property.
Change-Id: I927625fbcc02c4a875a1f39850b51576f5ff6c66
2 files changed
tree: 3958d67e586818a1f9741b7bc62487a41a44672a
  1. common/
  2. core/
  3. packaging/
  4. target/
  5. tests/
  6. tools/
  7. .gitignore
  8. buildspec.mk.default
  9. Changes.md
  10. CleanSpec.mk
  11. Deprecation.md
  12. envsetup.sh
  13. help.sh
  14. navbar.md
  15. OWNERS
  16. README.md
  17. tapasHelp.sh
  18. Usage.txt
README.md

Android Make Build System

This is the Makefile-based portion of the Android Build System.

For documentation on how to run a build, see Usage.txt

For a list of behavioral changes useful for Android.mk writers see Changes.md

For an outdated reference on Android.mk files, see build-system.html. Our Android.mk files look similar, but are entirely different from the Android.mk files used by the NDK build system. When searching for documentation elsewhere, ensure that it is for the platform build system -- most are not.

This Makefile-based system is in the process of being replaced with Soong, a new build system written in Go. During the transition, all of these makefiles are read by Kati, and generate a ninja file instead of being executed directly. That's combined with a ninja file read by Soong so that the build graph of the two systems can be combined and run as one.