include: Fixes to make the headers friendly with the latest wikiheaders.

include/SDL_thread.h

@@ -72,7 +72,7 @@ typedef unsigned int SDL_TLSID;
  *
  *  \note On many systems you require special privileges to set high or time critical priority.
  */
-typedef enum {
+typedef enum SDL_ThreadPriority {
     SDL_THREAD_PRIORITY_LOW,
     SDL_THREAD_PRIORITY_NORMAL,
     SDL_THREAD_PRIORITY_HIGH,