Use min/max instead of MIN/MAX.

diff --git a/server/registry.c b/server/registry.c
index 00b9ae5..5173f1c 100644
--- a/server/registry.c
+++ b/server/registry.c
@@ -350,7 +350,7 @@
 static void touch_key( struct key *key )
 {
     key->modif = time(NULL);
-    key->level = MAX( key->level, current_level );
+    key->level = max( key->level, current_level );
 }
 
 /* try to grow the array of subkeys; return 1 if OK, 0 on error */
@@ -1186,7 +1186,7 @@
     value->len  = len;
     value->type = type;
     /* update the key level but not the modification time */
-    key->level = MAX( key->level, current_level );
+    key->level = max( key->level, current_level );
     return 1;
 
  error: