Move Locale methods to locale.c source module
diff --git a/MagickCore/splay-tree.c b/MagickCore/splay-tree.c
index fadbc82..36d8167 100644
--- a/MagickCore/splay-tree.c
+++ b/MagickCore/splay-tree.c
@@ -51,6 +51,7 @@
 #include "MagickCore/studio.h"
 #include "MagickCore/exception.h"
 #include "MagickCore/exception-private.h"
+#include "MagickCore/locale_.h"
 #include "MagickCore/log.h"
 #include "MagickCore/memory_.h"
 #include "MagickCore/splay-tree.h"