drop spurious change

mpi/src/starpu_mpi_private.c

@@ -19,7 +19,7 @@
 
 int _starpu_debug_rank=-1;
 int _starpu_debug_level_min=0;
-int _starpu_debug_level_max=2;
+int _starpu_debug_level_max=0;
 int _starpu_mpi_tag = 42;
 int _starpu_mpi_comm;