Fixed an bf code execution error when newline is followed by EOF.

Normally, input file / stream will have an EOF after a newline
character like this:

CCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCC
DCCCCCCCCCCCCC
[EOF]

Before this fix, the code marked as 'D' in the example will be run
again, which is clearly an error.

You will not see such result after this fix is applied.