We don't need the "readonly" field of this struct, because it was only used
to protect flushes on non-writable handles, but PHYSFS_flush() also keeps
track of what's read-only and won't call into the platform layer anyhow.
HANDLEs are typedef'd to be "void *" on Windows, so this is safe (so long as
we check for INVALID_HANDLE_VALUE, which is ((void*)-1), when creating new
handles.
So now you can drop this into your program and not worry about filename
conflicts, or where "platform_unix.c" came from in the debugger, etc.
Also renamed the "beos" sources to "haiku" and "macosx" to "macos" to match
modern platform names.
Ryan C. Gordon