[physfs] iOS write fails

[Ryan C. Gordon]

> I have a may be simple question.
> I use physfs unter iOS and can read files :), with this search path line:
> PHYSFS_addToSearchPath(PHYSFS_getBaseDir());
> Writing does not work at all using that write dir:
> PHYSFS_setWriteDir(PHYSFS_getBaseDir());

The Base Directory--where your app is installed--is not writable on iOS.

The current code is doing it wrong on iOS, which I'll fix, but this is 
what you would need in PhysicsFS 2.1...

     PHYSFS_setWriteDir(PHYSFS_getPrefDir("Artem", "My Game"));

--ryan.