Improve redbean

- Improve serialization
- Add Benchmark() API to redbean
- Refactor UNIX API to be assert() friendly
- Make the redbean Lua REPL print data structures
- Fix recent regressions in linenoise reverse search
- Add -i flag so redbean can be a language interpreter

libc/calls/fstatat-sysv.c

@@ -28,6 +28,7 @@
  */
 int32_t sys_fstatat(int32_t dirfd, const char *path, struct stat *st,
                     int32_t flags) {
+  int rc;
   void *p;
   union metastat ms;
   if (IsAsan() && !__asan_is_valid(path, 1)) return efault();