Use dynamic linking for RocksDB when building electrs

[romanz]

Following https://github.com/romanz/electrs/blob/master/doc/install.md

[romanz]

CC: @Kixunil @openoms

[romanz]

Haven't tested it on an actual RPi devce, but it should (hopefully) work 🤞

[Kixunil]

Code looks OK

[openoms]

It is building ok without errors and faster due to having rocksdb already:

$ time config.scripts/bonus.electrs.sh on
real    25m46.872s                                  
user    50m13.638s                                  
sys     1m43.499s  

but when started running into this:
romanz/electrs#616

admin@raspberrypi:~ $ sudo -u electrs /home/electrs/electrs/target/release/electrs
Starting electrs 0.9.3 on aarch64 linux with Config { network: Bitcoin, db_path: "/mnt/hdd/app-storage/electrs/db/bitcoin", daemon_dir: "/home/electrs/.bitcoin", daemon_auth: UserPass("raspibolt", "<sensitive>"), daemon_rpc_addr: 127.0.0.1:8332, daemon_p2p_addr: 127.0.0.1:8333, electrum_rpc_addr: 127.0.0.1:50001, monitoring_addr: 127.0.0.1:4224, wait_duration: 10s, jsonrpc_timeout: 15s, index_batch_size: 10, index_lookup_limit: Some(200), reindex_last_blocks: 0, auto_reindex: true, ignore_mempool: false, sync_once: false, disable_electrum_rpc: false, server_banner: "Welcome to electrs v0.9.3 - the Electrum Rust Server on your RaspiBlitz", args: [] }
Illegal instruction

Same when installing Rust with:
sudo apt install cargo -y

[romanz]

Marking as "draft" until romanz/electrs#616 is resolved :(