Fixed typo in the comment

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404469

include/SDL_surface.h

@@ -74,7 +74,7 @@ typedef struct SDL_Surface
     int pitch;                  /**< Read-only */
     void *pixels;               /**< Read-write */
 
-    /** Application data associated with the surfade */
+    /** Application data associated with the surface */
     void *userdata;             /**< Read-write */
 
     /** information needed for surfaces requiring locks */