BigEndian: fix code that generates illegal instruction with gcc-4.9.2 on powerpc

Program received signal SIGILL, Illegal instruction.
X11_InitKeyboard (_this=0x1001f8f0)
    at /home/sdl/SDL_git/src/video/x11/SDL_x11keyboard.c:273
273	    XKeyboardState values = { .global_auto_repeat = AutoRepeatModeOff };

src/video/x11/SDL_x11keyboard.c

@@ -267,7 +267,9 @@ X11_InitKeyboard(_THIS)
     int best_index;
     int distance;
     Bool xkb_repeat = 0;
-    XKeyboardState values = { .global_auto_repeat = AutoRepeatModeOff };
+    XKeyboardState values;
+    SDL_zero(values);
+    values.global_auto_repeat = AutoRepeatModeOff;
     
     X11_XGetKeyboardControl(data->display, &values);
     if (values.global_auto_repeat != AutoRepeatModeOn)