Don't emit ESC [ n C with n=0.

This fixes a bug introduced with ANSI.SYS compatibility.
When we want to move at a specific column, we need to emit the sequence
to move the cursor to the right (after we moved 999 positions to the left)
only if we want to actually move right at least 1 position, since a
count of zero will still move the cursor one position to the right.