perf: exit(0) on view command to avoid destructors

it is unecessary to run destructures since the OS will cleanup
everything for us and it saved a bit of time.

Benchmark 1: ./fctdrive-noexit view
  Time (mean ± σ):      37.0 ms ±   1.2 ms    [User: 29.4 ms, System: 7.4 ms]
  Range (min … max):    35.7 ms …  40.8 ms    81 runs

Benchmark 2: ./fctdrive-exit view
  Time (mean ± σ):      34.7 ms ±   1.3 ms    [User: 26.9 ms, System: 7.6 ms]
  Range (min … max):    33.0 ms …  38.5 ms    83 runs

Summary
  ./fctdrive-exit view ran
    1.07 ± 0.05 times faster than ./fctdrive-noexit view

1 files changed, 1 insertions, 0 deletions

diff --git a/fctdrive/src/main.rs b/fctdrive/src/main.rs
index 2035680..91e5046 100644
--- a/fctdrive/src/main.rs
+++ b/fctdrive/src/main.rs
@@ -859,6 +859,7 @@ fn cmd_view(args: ViewArgs) {
     ops.iter().for_each(|op| apply(&mut fs, op).unwrap());
     write_node(&mut writer, &fs, fs.root, Default::default());
     writer.flush().unwrap();
+    std::process::exit(0);
 }
 
 fn write_node(writer: &mut FsNodeWriter, fs: &Fs, node_id: FsNodeId, path: DrivePath) {