Rename EXTRACT_QUOTES to EXTRACT_UNQUOTE

Whenever I see EXTRACT_QUOTES, I'm always confused whether it means to
leave the quotes in or to take them out. Let's say "unquote", like we
say "cunescape".

src/shared/mount-util.c

@@ -505,7 +505,7 @@ int mount_option_mangle(
                 _cleanup_free_ char *word = NULL;
                 const struct libmnt_optmap *ent;
 
-                r = extract_first_word(&p, &word, ",", EXTRACT_QUOTES);
+                r = extract_first_word(&p, &word, ",", EXTRACT_UNQUOTE);
                 if (r < 0)
                         return r;
                 if (r == 0)