This changes windows_thread_info::name to be a unique_xmalloc_ptr,
removing some manual memory management.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (handle_exception)
(windows_nat_target::thread_name): Update.
* nat/windows-nat.h (windows_thread_info): Remove destructor.
<name>: Now unique_xmalloc_ptr.