avoid trailing whitespace in zero-change diffstat lines

In some cases, we produce a diffstat line even though no
lines have changed (e.g., because of an exact rename). In
this case, there is no +/- "graph" after the number of
changed lines. However, we output the space separator
unconditionally, meaning that these lines contained a
trailing space character.

This isn't a huge problem, but in cleaning up the output we
are able to eliminate some trailing whitespace from a test
vector.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -922,7 +922,8 @@ static void show_stats(struct diffstat_t* data, struct diff_options *options)
 			total = add + del;
 		}
 		show_name(options->file, prefix, name, len, reset, set);
-		fprintf(options->file, "%5d ", added + deleted);
+		fprintf(options->file, "%5d%s", added + deleted,
+				added + deleted ? " " : "");
 		show_graph(options->file, '+', add, add_c, reset);
 		show_graph(options->file, '-', del, del_c, reset);
 		fprintf(options->file, "\n");

t/t4016-diff-quote.sh

@@ -53,13 +53,13 @@ test_expect_success 'git diff --summary -M HEAD' '
 '
 
 cat >expect <<\EOF
- pathname.1 => "Rpathname\twith HT.0"            |    0 
- pathname.3 => "Rpathname\nwith LF.0"            |    0 
- "pathname\twith HT.3" => "Rpathname\nwith LF.1" |    0 
- pathname.2 => Rpathname with SP.0               |    0 
- "pathname\twith HT.2" => Rpathname with SP.1    |    0 
- pathname.0 => Rpathname.0                       |    0 
- "pathname\twith HT.0" => Rpathname.1            |    0 
+ pathname.1 => "Rpathname\twith HT.0"            |    0
+ pathname.3 => "Rpathname\nwith LF.0"            |    0
+ "pathname\twith HT.3" => "Rpathname\nwith LF.1" |    0
+ pathname.2 => Rpathname with SP.0               |    0
+ "pathname\twith HT.2" => Rpathname with SP.1    |    0
+ pathname.0 => Rpathname.0                       |    0
+ "pathname\twith HT.0" => Rpathname.1            |    0
  7 files changed, 0 insertions(+), 0 deletions(-)
 EOF
 test_expect_success 'git diff --stat -M HEAD' '