Fix bugs and make improvements to redbean

- Abort if .init.lua fails
- Refactor redbean to use new append library
- Use first certificate if SNI routing fails
- Use function/data sections when building Lua
- Don't use self-signed auto-generated cert for client
- Add -D staging dirs to redbean lua module default path

libc/stdio/vappendf.c

@@ -25,9 +25,9 @@
 #define W sizeof(size_t)
 
 /**
- * Appends data to buffer.
+ * Appends formatted string to buffer.
  */
-int(vappendf)(char **b, const char *f, va_list v) {
+ssize_t(vappendf)(char **b, const char *f, va_list v) {
   char *p;
   int r, s;
   va_list w;