fix spurious test failure with panic=abort

tests/ui/panic-handler/weak-lang-item-2.rs

@@ -6,10 +6,18 @@
 
 extern crate weak_lang_items as other;
 
-use std::thread;
-
 fn main() {
-    let _ = thread::spawn(move|| {
+    let _ = std::thread::spawn(move || {
+        // The goal of the test is just to make sure other::foo() is called. Since the function
+        // panics, it's executed in its own thread. That way, the panic is isolated within the
+        // thread and wont't affect the overall exit code.
+        //
+        // That causes a spurious failures in panic=abort targets though: if the program exits
+        // before the thread is fully initialized the test will pass, but if the thread gets
+        // executed first the whole program will abort. Adding a 60 seconds sleep will (hopefully!)
+        // ensure the program always exits before the thread is executed.
+        std::thread::sleep(std::time::Duration::from_secs(60));
+
         other::foo()
     });
 }