Remove extra newline that leads to linter warning
D3979 removed the freopen() function and leaded to an extra newline.
Most likely the linter did some other autofix that made this being
hidden at submission time.
Should return no error:
arc lint --everything
Reviewers: #bitcoin_abc, deadalnix, jasonbcox
Reviewed By: #bitcoin_abc, jasonbcox
Differential Revision: https://reviews.bitcoinabc.org/D3999