Add ProductDirectory variable to soong_config.mk

Bug: 297269187
Test: m nothing
Change-Id: Ib14ce9d911c86afb5bb770c4b05977021e771c0f
diff --git a/core/soong_config.mk b/core/soong_config.mk
index e00447a..5bcdfce 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -319,6 +319,10 @@
 
 $(call add_json_bool, CheckVendorSeappViolations, $(filter true,$(CHECK_VENDOR_SEAPP_VIOLATIONS)))
 
+$(call add_json_map, PartitionVars)
+  $(call add_json_str,  ProductDirectory,    $(dir $(INTERNAL_PRODUCT)))
+$(call end_json_map)
+
 $(call json_end)
 
 $(file >$(SOONG_VARIABLES).tmp,$(json_contents))