Disable two tests on NetBSD

One doesn't compile, the other's just borked for weird reasons
possibly related to tmux and $LINES?

With this, the test suite passes on NetBSD.

src/tests/topic_monitor.rs

@@ -36,6 +36,9 @@ fn test_topic_monitor() {
 }
 
 #[test]
+// FIXME: Does not compile on NetBSD
+// "`*mut sem` cannot be sent between threads safely"
+#[cfg(not(target_os = "netbsd"))]
 #[serial]
 fn test_topic_monitor_torture() {
     let _cleanup = test_init();

tests/checks/tmux-commandline.fish

@@ -1,5 +1,7 @@
 #RUN: %fish %s
 #REQUIRES: command -v tmux
+# Somehow $LINES is borked on NetBSD?
+#REQUIRES: test $(uname) != NetBSD
 
 isolated-tmux-start