Declare unused parameters

When building with global CFLAGS=-Wunused-parameter the output from the
build looks terrible.  This commit explicitly declares unused variables
to prevent triggering -Wunused-parameter

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/tmpfiles.c

@@ -114,6 +114,9 @@ static int parse_mm(char *arg, int *major, int *minor)
 
 static int do_delete(const char *fpath, const struct stat *sb, int tflag, struct FTW *ftw)
 {
+	(void)sb;
+	(void)tflag;
+
 	if (ftw->level == 0)
 		return 1;