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

tool/emacs/cosmo-c-builtins.el

@@ -269,7 +269,13 @@
            "__builtin_bcmp"
            "__builtin_bzero"
            "__builtin_memset"
-           "__builtin_strlen"))
+           "__builtin_strlen"
+           "__ATOMIC_RELAXED"
+           "__ATOMIC_CONSUME"
+           "__ATOMIC_ACQUIRE"
+           "__ATOMIC_RELEASE"
+           "__ATOMIC_ACQ_REL"
+           "__ATOMIC_SEQ_CST"))
 
         (gcc-builtin-functions-atomic
          '("__atomic_load_n"