Remove windows_thread_info destructor
windows_thread_info declares and defines a destructor, but this
doesn't need to be explicit.
diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c
index 21445f3..3907286 100644
--- a/gdb/nat/windows-nat.c
+++ b/gdb/nat/windows-nat.c
@@ -74,10 +74,6 @@ GenerateConsoleCtrlEvent_ftype *GenerateConsoleCtrlEvent;
   debug_prefixed_printf_cond (debug_events, "windows events", fmt, \
 			      ## __VA_ARGS__)
 
-windows_thread_info::~windows_thread_info ()
-{
-}
-
 void
 windows_thread_info::suspend ()
 {
diff --git a/gdb/nat/windows-nat.h b/gdb/nat/windows-nat.h
index f0abd7d..bfb359e 100644
--- a/gdb/nat/windows-nat.h
+++ b/gdb/nat/windows-nat.h
@@ -43,8 +43,6 @@ struct windows_thread_info
   {
   }
 
-  ~windows_thread_info ();
-
   DISABLE_COPY_AND_ASSIGN (windows_thread_info);
 
   /* Ensure that this thread has been suspended.  */