engine: platform: implement generic GetNativeObject for POSIX systems without SDL2

engine/platform/linux/vid_fbdev.c

@@ -272,11 +272,6 @@ void Platform_RunEvents( void )
 
 }
 
-void *Platform_GetNativeObject( const char *name )
-{
-	return NULL;
-}
-
 void GAME_EXPORT Platform_GetMousePos( int *x, int *y )
 {
 	*x = *y = 0;

engine/platform/posix/sys_posix.c

@@ -147,12 +147,20 @@ void Posix_Daemonize( void )
 }
 
 #if !XASH_SDL && !XASH_ANDROID
-
 void Platform_Init( void )
 {
 	Posix_Daemonize();
 }
-void Platform_Shutdown( void ) {}
+
+void Platform_Shutdown( void )
+{
+
+}
+
+void *Platform_GetNativeObject( const char *name )
+{
+	return NULL;
+}
 #endif
 
 #if XASH_TIMER == TIMER_POSIX