blame: make sure that the last line ends in an LF

blame: make sure that the last line ends in an LF

This is convenient when parsing multiple the blame of multiple files,
for example:

    git ls-files -z --exclude-standard -- "*.[ch]" |
    xargs --null -n 1 git blame -p > output

and then analyzing the 'output' file using a seperate script.

Currently the parsing is difficult when not all files have a newline
at EOF, this patch ensures that even such files have a newline at the
end of the blame output.

Signed-off-by: Sverre Rabbelier <redacted>
CC: Johannes Schindelin <redacted>
Signed-off-by: Junio C Hamano <redacted>