Make GSI target to export bootimage to DIST

This is to support a bootimage only target in AB.

Bug: 198363484
Test: lunch aosp_arm64-userdebug; make bootimage dist

Change-Id: I9a32c365f635ec4693675a1969d7a1e684c8f55a
diff --git a/core/main.mk b/core/main.mk
index 8ba1396..de9e2e7 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1596,6 +1596,10 @@
 .PHONY: bootimage
 bootimage: $(INSTALLED_BOOTIMAGE_TARGET)
 
+ifeq (true,$(PRODUCT_EXPORT_BOOT_IMAGE_TO_DIST))
+$(call dist-for-goals, bootimage, $(INSTALLED_BOOTIMAGE_TARGET))
+endif
+
 .PHONY: bootimage_debug
 bootimage_debug: $(INSTALLED_DEBUG_BOOTIMAGE_TARGET)
 
diff --git a/core/product.mk b/core/product.mk
index 79d22b1..c2a83fd 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -274,6 +274,7 @@
 
 # Boot image options.
 _product_single_value_vars += \
+    PRODUCT_EXPORT_BOOT_IMAGE_TO_DIST \
     PRODUCT_USE_PROFILE_FOR_BOOT_IMAGE \
     PRODUCT_DEX_PREOPT_BOOT_IMAGE_PROFILE_LOCATION \
     PRODUCT_USES_DEFAULT_ART_CONFIG \
diff --git a/target/product/gsi_release.mk b/target/product/gsi_release.mk
index 014366d..d0a98c0 100644
--- a/target/product/gsi_release.mk
+++ b/target/product/gsi_release.mk
@@ -71,6 +71,7 @@
 PRODUCT_BUILD_VENDOR_IMAGE := false
 PRODUCT_BUILD_SUPER_PARTITION := false
 PRODUCT_BUILD_SUPER_EMPTY_IMAGE := false
+PRODUCT_EXPORT_BOOT_IMAGE_TO_DIST := true
 
 # Always build modules from source
 MODULE_BUILD_FROM_SOURCE := true