[physfs] abs-file.h patch

[Ryan C. Gordon]

> Here's an update patch for the abs-file.h contrib.  The patch
> adds MY_SEEK() (warning: /might/ be renamed in the future),
> MY_TELL(), and a probably-less-sucky stub for MY_SETBUFFER() in
> the stdio case.

It's in CVS. Thanks!

--ryan.