Mark it as unistallable

So the build system can take it as a static Java library instead of a
shared Java library (.jar with classes.dex).

Change-Id: I5213b34dab8688c8e0dee49a17fadd7b9d29c9c2
(cherry-pick from commit a9f2cdb3bee47e31289e3acc5554fc6e704c2add)