Till now, prebuilt_etc has to be installable to be packaged. With this commit, packaging modules like filesystem now can include uninstallable prebuilt_etc. This can help when prebuilt_etc can conflict with other partitions e.g. system. Bug: 179340780 Test: build filesystem with uninstallable prebuilt_etc Change-Id: Id981fe7ce41f1189eb0f85f2d1677d973004423c