16384 makes workers sleep for almost a whole ms, this is way too much. Keep not-too-intrusive value in the trunk for now

src/drivers/driver_common/driver_common.c

@@ -29,8 +29,8 @@
 #include <core/debug.h>
 
 
-#define BACKOFF_MAX 16384  /* TODO : use parameter to define them */
-#define BACKOFF_MIN 32
+#define BACKOFF_MAX 32  /* TODO : use parameter to define them */
+#define BACKOFF_MIN 1
 
 void _starpu_driver_start_job(struct _starpu_worker *args, struct _starpu_job *j, struct timespec *codelet_start, int rank, int profiling)
 {