Fixed some __BEOS__ vs __HAIKU__ preprocessor tests (thanks, Axel!).

Fixes Bugzilla #1773.

src/SDL.c

@@ -371,9 +371,6 @@ SDL_GetPlatform()
     return "AIX";
 #elif __ANDROID__
     return "Android";
-#elif __HAIKU__
-/* Haiku must appear here before BeOS, since it also defines __BEOS__ */
-    return "Haiku";
 #elif __BEOS__
     return "BeOS";
 #elif __BSDI__
@@ -382,6 +379,8 @@ SDL_GetPlatform()
     return "Dreamcast";
 #elif __FREEBSD__
     return "FreeBSD";
+#elif __HAIKU__
+    return "Haiku";
 #elif __HPUX__
     return "HP-UX";
 #elif __IRIX__

src/events/SDL_sysevents.h

@@ -24,7 +24,8 @@
 
 /* Useful functions and variables from SDL_sysevents.c */
 
-#ifdef __BEOS__                 /* The Be event loop runs in a separate thread */
+#if defined(__BEOS__) || defined(__HAIKU__) 
+/* The Be and Haiku event loops run in a separate thread */
 #define MUST_THREAD_EVENTS
 #endif