soong: Add flag for fod extension

Change-Id: Ib45706cc50fa88b9b05af1c68eec9d1f08d70569
diff --git a/build/soong/soong_config.mk b/build/soong/soong_config.mk
index 957167b..6f28db5 100644
--- a/build/soong/soong_config.mk
+++ b/build/soong/soong_config.mk
@@ -12,6 +12,7 @@
 $(call add_json_bool, Target_motorized_camera,                $(filter true,$(TARGET_MOTORIZED_CAMERA)))
 $(call add_json_str_omitempty, Target_init_vendor_lib, 	      $(TARGET_INIT_VENDOR_LIB))
 $(call add_json_bool, Target_enforce_ab_ota_partition_list,   $(filter true,$(TARGET_ENFORCE_AB_OTA_PARTITION_LIST)))
+$(call add_json_str_omitempty, Target_surfaceflinger_fod_lib, $(TARGET_SURFACEFLINGER_FOD_LIB))
 
 # This causes the build system to strip out the last comma in our nested struct, to keep the JSON valid.
 _json_contents := $(_json_contents)__SV_END