Fix symbol zip creation with OUT_DIR outside source

Bug: 34818739
Test: OUT_DIR=/... m -j /.../aosp_arm64-symbols-eng.dwillemsen.zip
Change-Id: I1d0d3a9f70d3457a536dee6fc25f49a16c353ae8
diff --git a/core/Makefile b/core/Makefile
index 87e230a..d20da22 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2196,7 +2196,7 @@
 	$(hide) rm -rf $@ $(PRIVATE_LIST_FILE)
 	$(hide) mkdir -p $(dir $@) $(TARGET_OUT_UNSTRIPPED) $(dir $(PRIVATE_LIST_FILE))
 	$(hide) find $(TARGET_OUT_UNSTRIPPED) | sort >$(PRIVATE_LIST_FILE)
-	$(hide) $(SOONG_ZIP) -d -o $@ -C . -l $(PRIVATE_LIST_FILE)
+	$(hide) $(SOONG_ZIP) -d -o $@ -C $(OUT_DIR)/.. -l $(PRIVATE_LIST_FILE)
 # -----------------------------------------------------------------
 # A zip of the coverage directory.
 #