Make redbean StoreAsset() work better

- Better UBSAN error messages
- POSIX Advisory Locks polyfills
- Move redbean manual to /.help.txt
- System call memory safety in ASAN mode
- Character classification now does UNICODE

libc/calls/getppid.c

@@ -22,7 +22,7 @@
  * Returns parent process id.
  * @asyncsignalsafe
  */
-int32_t getppid(void) {
+int getppid(void) {
   if (!IsWindows()) {
     if (!IsNetbsd()) {
       return sys_getppid();