keystore2: Statically link Rust libs to save RAM

While dynamic linkage scales better, `keystore2` is the only process
currently using dynamic Rust libraries in S. Given this, it makes more
sense to statically link its dependencies to save RAM for now.

This shaves about 4.1M RSS from a running `keystore2` at time of
writing.

Test: m, boot, showmap on keystore2
Bug: 186601681
Bug: 183785247
Change-Id: I0684a8959ab136432e6a932dddafe2a765ad0c8c
1 file changed