uncrypt: Depend on commonly used shared libs.

We already have these shared libraries on device. And `uncrypt` doesn't
need to be statically linked (it wasn't, even prior to this change).

With this change, the size of uncrypt goes down from 139KiB to 33KiB
(aosp_marlin-userdebug).

Test: Build and flash on marlin. Trigger a factory reset (which calls
      `uncrypt` to set up the BCB).
Change-Id: I77e3c82e8ce3734019da75c48928d881cb7ef0f0