Export PRODUCT_FSVERITY_GENERATE_METADATA to soong

This will be used to conditionally generate fsv_meta files in the
autogenerated soong partitions.

Test: lunch sdk_phone64_x86_64-trunk_staging-userdebug
Test: Ran the diff test tool on autogenerated soong system image
Change-Id: I9b7487d49fae079fa8e6ba3a89712da56ad4ed71
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 0dd91cc..d94fa15 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -497,6 +497,9 @@
 
   $(call add_json_list, ProductCopyFiles, $(PRODUCT_COPY_FILES))
 
+  # Used to generate fsv meta
+  $(call add_json_bool, ProductFsverityGenerateMetadata,               $(PRODUCT_FSVERITY_GENERATE_METADATA))
+
 $(call end_json_map)
 
 # For converting vintf_data