storyboard.c: fix compilation with optimisations disabled.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@3400 92316355-f0b4-4df1-b90c-862c8a59935f

examples/storyboard.c

@@ -217,7 +217,7 @@ static void decorate(uint8_t *img)
 {
     static int const hi = 200;
     static int const lo = 50;
-    static int const mid = (hi + lo) / 2;
+    static int const mid = 127;
     int x, y;
 
     for(y = 0; y < THEIGHT; y++)