AAPT2: Fix order-of-destruction crash

Make sure that users of StringPool are destroyed before
the StringPool itself.

Test: valgrind aapt2 optimize -o opt.apk out/target/common/obj/APPS/framework-res_intermediates/package-export.apk
Change-Id: I140c2d32f8449028976795d5d6865d83e1409b53
3 files changed