Adding needs-unwind for test using panic::catch_unwind

Author: andrewpollack

src/test/ui/issues/issue-87707.rs

@@ -3,6 +3,7 @@
 // run-fail
 // exec-env:RUST_BACKTRACE=0
 // check-run-results
+// needs-unwind uses catch_unwind
 
 use std::sync::Once;
 use std::panic;

src/test/ui/issues/issue-87707.run.stderr

@@ -1,3 +1,3 @@
-thread 'main' panicked at 'Here Once instance is poisoned.', $DIR/issue-87707.rs:13:24
+thread 'main' panicked at 'Here Once instance is poisoned.', $DIR/issue-87707.rs:14:24
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
-thread 'main' panicked at 'Once instance has previously been poisoned', $DIR/issue-87707.rs:15:7
+thread 'main' panicked at 'Once instance has previously been poisoned', $DIR/issue-87707.rs:16:7