this little patch brings a significant speed improvement to
the bximage utility. when bximage creates a disk image, it writes
a lot of zeros. actually as much zeros as the size of the image file.
this takes quite a while for large images (at least in my win98/cygwin box).
a faster way to create the image file is to seek to its end and write a
single byte.
to see the speed improvement, create a 100mb image with the old bximge.
then apply this patch and do the same.
removed unused variables, initialized things that I had missed before,
added a missing arg to sprintf, and a return at the end of int main.
That's all.
