Support for recovery snapshot.

Bug: 171231437
Test: source build/envsetup.sh
Test: ALLOW_MISSING_DEPENDENCIES=true m -j nothing
Change-Id: I6dbcf21ee26c53cd3ac573d118a99d68161aa2c7
diff --git a/core/soong_config.mk b/core/soong_config.mk
index ae494c4..c01681d 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -129,6 +129,7 @@
 $(call add_json_str,  ProductVndkVersion,                $(PRODUCT_PRODUCT_VNDK_VERSION))
 $(call add_json_list, ExtraVndkVersions,                 $(PRODUCT_EXTRA_VNDK_VERSIONS))
 $(call add_json_list, DeviceSystemSdkVersions,           $(BOARD_SYSTEMSDK_VERSIONS))
+$(call add_json_str,  RecoverySnapshotVersion,           $(RECOVERY_SNAPSHOT_VERSION))
 $(call add_json_list, Platform_systemsdk_versions,       $(PLATFORM_SYSTEMSDK_VERSIONS))
 $(call add_json_bool, Malloc_not_svelte,                 $(call invert_bool,$(filter true,$(MALLOC_SVELTE))))
 $(call add_json_bool, Malloc_zero_contents,              $(call invert_bool,$(filter false,$(MALLOC_ZERO_CONTENTS))))