On Unix, the easiest way to implement RESIZE-FILE would be to call
ftruncate, but in ANSI C alone it's quite difficult. As this takes a
bit more code, I created a new file pf_fileio_stdio.c and moved it
there. The idea is that somebody could replace that with say a
pf_fileio_posix.c and use ftruncate there.
Because there's a new file I had to change the Makefiles. I did not
fix the VisualStudio project file, as I don't know how to do that.