Improve synchronization

- Fix bugs in kDos2Errno definition
- malloc() should now be thread safe
- Fix bug in rollup.com header generator
- Fix open(O_APPEND) on the New Technology
- Fix select() on the New Technology and test it
- Work towards refactoring i/o for thread safety
- Socket reads and writes on NT now poll for signals
- Work towards i/o completion ports on the New Technology
- Make read() and write() intermittently check for signals
- Blinkenlights keyboard i/o so much better on NT w/ poll()
- You can now poll() files and sockets at the same time on NT
- Fix bug in appendr() that manifests with dlmalloc footers off

libc/stdio/tmpfile.c

@@ -19,7 +19,6 @@
 #include "libc/bits/safemacros.internal.h"
 #include "libc/calls/calls.h"
 #include "libc/fmt/fmt.h"
-#include "libc/intrin/kprintf.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/stdio/stdio.h"