port r14801 from 1.2: disable checking on memory availability probing

src/datawizard/memory_manager.c

@@ -126,10 +126,14 @@ starpu_ssize_t starpu_memory_get_total(unsigned node)
 
 starpu_ssize_t starpu_memory_get_available(unsigned node)
 {
+	starpu_ssize_t ret;
 	if (global_size[node] == 0)
 		return -1;
-	else
-		return global_size[node] - used_size[node];
+
+	STARPU_HG_DISABLE_CHECKING(used_size[node]);
+	ret = global_size[node] - used_size[node];
+	STARPU_HG_ENABLE_CHECKING(used_size[node]);
+	return ret;
 }
 
 void starpu_memory_wait_available(unsigned node, size_t size)