[tlbuild] dvi test?

[Karl Berry]

Thanks Bruno.

     3208/0x31ed:  ftruncate(0x6, 0x0, 0x0)		 = 0 0
     3208/0x31ed:  lseek(0x6, 0xFFFFFFFFFFFFF7C7, 0x1)		 = -1 Err#22

fseek (aka lseek) should presumably not be getting called with that
strangely huge value (-something?) right after ftruncate has truncated
it to empty.

ftruncate is only used directly in one place in xdvi: dvi-init.c
line 1193:
	if (ftruncate(tmp_fd, 0) < 0) {
	  <failure code>
	}
	fseek(target_fp, 0L, SEEK_SET);
	fseek(source_fp, 0L, SEEK_SET);
	
I think it would be a good idea to check the return values from those
fseeks. My brain is too wiped (got ftruncated today I guess :) to commit
the change now, even though it is trivial ... --thanks, karl.