Raise the default test timeout to 60 seconds

The 80k-section tests take about 2 seconds alone but 13 to 14 seconds
on every target when the suite runs 128 jobs at once, so any other load
on the machine pushed some of them past 30 seconds. The limit exists to
catch hangs, and 60 seconds still does that promptly.

tests/lib.rs

@@ -19,7 +19,7 @@ use std::time::{Duration, Instant};
 #[cfg(unix)]
 use std::os::unix::process::CommandExt;
 
-const DEFAULT_TIMEOUT: Duration = Duration::from_secs(30);
+const DEFAULT_TIMEOUT: Duration = Duration::from_secs(60);
 
 #[derive(Clone, Copy)]
 struct TargetSpec {