[MI non-stop 03/11, RFA] Discard cleanup when deferring displaced step

[Vladimir Prus <vladimir@codesourcery.com>]

My MI non-stop tests (coming later in the series) revealed a bug in displaced
stepping -- we fail to discard cleanup on an early exit path, which caused a
call to normal_stop at very unfortunate time -- when a thread was running.

OK?

- Volodya

	* infrun.c (resume): Discard cleanups on early exit path.
---
 gdb/infrun.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/gdb/infrun.c b/gdb/infrun.c
index cf23c18..e803d1b 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -964,10 +964,13 @@ a command like `return' or `jump' to continue execution."));
       && sig == TARGET_SIGNAL_0)
     {
       if (!displaced_step_prepare (inferior_ptid))
-	/* Got placed in displaced stepping queue.  Will be resumed
-	   later when all the currently queued displaced stepping
-	   requests finish.  */
-	return;
+	{
+	  /* Got placed in displaced stepping queue.  Will be resumed
+	     later when all the currently queued displaced stepping
+	     requests finish.  */
+	  discard_cleanups (old_cleanups);
+	  return;
+	}
     }
 
   if (step && gdbarch_software_single_step_p (gdbarch))
-- 
1.5.3.5