Add A/B update to GSI

The feature should work fine on the devices with partition _a and _b.
and will not be enabled on the devices without partition _a and _b.

Bug: 110763858
Test: build aosp_arm64-userdebug and aosp_arm64_ab-userdebug
Change-Id: I9f783dd6fe69eff2536a6aac0506e41c724510b2
Merged-In: I9f783dd6fe69eff2536a6aac0506e41c724510b2
diff --git a/target/product/aosp_x86.mk b/target/product/aosp_x86.mk
index b044149..7929a3e 100644
--- a/target/product/aosp_x86.mk
+++ b/target/product/aosp_x86.mk
@@ -14,6 +14,13 @@
 # limitations under the License.
 #
 
+# The system image of aosp_x86-userdebug is a GSI for the devices with:
+# - x86 32 bits user space
+# - 64 bits binder interface
+# - system-as-root
+# - VNDK enforcement
+# - compatible property override enabled
+
 PRODUCT_PROPERTY_OVERRIDES += \
 	rild.libpath=/vendor/lib/libreference-ril.so
 
@@ -28,6 +35,13 @@
 
 include $(SRC_TARGET_DIR)/product/full_x86.mk
 
+# Enable A/B update
+AB_OTA_UPDATER := true
+AB_OTA_PARTITIONS := system
+PRODUCT_PACKAGES += \
+    update_engine \
+    update_verifier
+
 # Needed by Pi newly launched device to pass VtsTrebleSysProp on GSI
 PRODUCT_COMPATIBLE_PROPERTY_OVERRIDE := true