off_t data type is unknown about pforth

[philburk]

What target are you building for?
What host are you building on?

[phmarek]

That's on Debian testing/unstable, amd64; not cross-compiling.

[philburk]

The use of off_t was added in this commit:
336369a

Because off_t is not very standard, I recommend replacing off_t with a new typedef that is based on int64_t.

Forth uses two cells to hold a seek offset, which will either be 64 or 128-bits in pForth.
We don't really need to go to 128-bit offsets so internally we can just always use 64.

[philburk]

To test the FILE words affected by this change.

s" ../../readme.txt"  r/o open-file . value FID

That should print 0

100 s>d fid reposition-file
fid file-position

Should return a position of 100

fid close-file

[philburk]

I decided to define file_offset_t as long because it is more compatible with stdout.

Pending fix here:
#44

[philburk]

This was fixed by #44