Make exciting improvements

- Add Lua backtraces to redbean!
- Wipe serving keys after redbean forks
- Audit redbean to remove free via exit
- Log SSL client ciphersuite preferences
- Increase ASAN malloc() backtrace depth
- Make GetSslRoots() behave as a singleton
- Move leaks.c from LIBC_TESTLIB to LIBC_LOG
- Add undocumented %n to printf() for newlines
- Fix redbean memory leak reindexing inode change
- Fix redbean memory leak with Fetch() DNS object
- Restore original environ after __cxa_finalize()
- Make backtrace always work after __cxa_finalize()
- Introduce COUNTEXPR() diagnostic / benchmark tool
- Fix a few more instances of errno being clobbered
- Consolidate the ANSI color disabling internal APIs

libc/fmt/dirname.c

@@ -24,7 +24,11 @@
 
 /**
  * Returns directory portion of path.
- * @param s is mutated
+ *
+ * This returns "." if path doesn't have slashes. If path is empty then
+ * this returns empty string.
+ *
+ * @param s is mutated and must not be NULL
  */
 char *dirname(char *s) {
   size_t i, n;