Export BUILDING_ODM_IMAGE to soong

If true, soong will autogenerate a partition module for odm.img

Bug: 376755916
Test: verified that a odm partition soong module is created by
build/soong/fsgen

Change-Id: I3b286cbe06122a6ed52ad209f40154f43c1bb46c
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 988b5c1..9da1c7b 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -185,6 +185,7 @@
 $(call add_json_str,  VendorPath,                        $(TARGET_COPY_OUT_VENDOR))
 $(call add_json_bool, BuildingVendorImage,               $(BUILDING_VENDOR_IMAGE))
 $(call add_json_str,  OdmPath,                           $(TARGET_COPY_OUT_ODM))
+$(call add_json_bool, BuildingOdmImage,                  $(BUILDING_ODM_IMAGE))
 $(call add_json_str,  ProductPath,                       $(TARGET_COPY_OUT_PRODUCT))
 $(call add_json_bool, BuildingProductImage,              $(BUILDING_PRODUCT_IMAGE))
 $(call add_json_str,  SystemExtPath,                     $(TARGET_COPY_OUT_SYSTEM_EXT))