jtag: add jtag_flush_queue_sleep debug command

it can be useful to throttle performance: test
differences in behavior, test performance effect
of long roundtrips.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

src/jtag/jtag.h

@@ -311,6 +311,10 @@ int  adapter_init(struct command_context* cmd_ctx);
 /// Shutdown the debug adapter upon program exit.
 int  adapter_quit(void);
 
+/// Set ms to sleep after jtag_execute_queue() flushes queue. Debug
+/// purposes.
+void jtag_set_flush_queue_sleep(int ms);
+
 /**
  * Initialize JTAG chain using only a RESET reset. If init fails,
  * try reset + init.