Remove a bunch of unused variables

gcc does not warn about those, because of the _cleanup_ usage.
clang is smarter here.

src/basic/terminal-util.c

@@ -245,7 +245,6 @@ int ask_string(char **ret, const char *text, ...) {
 
 int reset_terminal_fd(int fd, bool switch_to_text) {
         struct termios termios;
-        _cleanup_free_ char *utf8 = NULL;
         int r = 0;
 
         /* Set terminal to some sane defaults */