Put system_version in target_files.zip

Bug: 35364984
Test: m dist
Change-Id: I309acb41eb85de239c4c1718e14d9442ca1b0408
(cherry picked from commit cea4d52d2fee19281e660943129e1ad3bdc51fef)
diff --git a/core/Makefile b/core/Makefile
index d5a2005..77bc2be 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2117,6 +2117,7 @@
 ifdef OSRELEASED_DIRECTORY
 	$(hide) $(ACP) $(TARGET_OUT_OEM)/$(OSRELEASED_DIRECTORY)/product_id $(zip_root)/META/product_id.txt
 	$(hide) $(ACP) $(TARGET_OUT_OEM)/$(OSRELEASED_DIRECTORY)/product_version $(zip_root)/META/product_version.txt
+	$(hide) $(ACP) $(TARGET_OUT_ETC)/$(OSRELEASED_DIRECTORY)/system_version $(zip_root)/META/system_version.txt
 endif
 endif
 ifeq ($(BREAKPAD_GENERATE_SYMBOLS),true)