test-genrandom: Add newline to usage string

A minor fix to place the terminal input on a new line if test-genrandom
is run with no arguments.

Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

test-genrandom.c

@@ -13,7 +13,7 @@ int main(int argc, char *argv[])
 	unsigned char *c;
 
 	if (argc < 2 || argc > 3) {
-		fprintf( stderr, "Usage: %s <seed_string> [<size>]", argv[0]);
+		fprintf(stderr, "Usage: %s <seed_string> [<size>]\n", argv[0]);
 		return 1;
 	}