i3: Replace loglevels by a global debug logging

File-limited were not used nor really useful
Besides, they are painful to maintain in Makefile rules compared to the
benefit

src/regex.c

@@ -67,7 +67,7 @@ void regex_free(struct regex *regex) {
 /*
  * Checks if the given regular expression matches the given input and returns
  * true if it does. In either case, it logs the outcome using LOG(), so it will
- * be visible without any debug loglevel.
+ * be visible without debug logging.
  *
  */
 bool regex_matches(struct regex *regex, const char *input) {