[gnome-calendar] month-view: fix mirroring macro

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 6afa9b98f63e2189d95b721e05beb6a1088e8077
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Tue Oct 27 11:57:51 2015 -0200

    month-view: fix mirroring macro
    
    It was using a local variable, which is a bad idea. It
    only worked because we were using it in the context of
    that local variable, but it was luck.

 src/gcal-month-view.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/gcal-month-view.c b/src/gcal-month-view.c
index c999de9..fdb77c5 100644
--- a/src/gcal-month-view.c
+++ b/src/gcal-month-view.c
@@ -89,7 +89,7 @@ enum
   PROP_DATE,  /* active-date inherited property */
 };
 
-#define MIRROR(val,start,end) (start + (val / end) * end + (end - cell % end))
+#define MIRROR(val,start,end) (start + (val / end) * end + (end - val % end))
 
 static gint           gather_button_event_data              (GcalMonthView  *view,
                                                              gdouble         x,