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/sock/ntstdin.internal.h

@@ -0,0 +1,24 @@
+#ifndef COSMOPOLITAN_LIBC_SOCK_NTSTDIN_INTERNAL_H_
+#define COSMOPOLITAN_LIBC_SOCK_NTSTDIN_INTERNAL_H_
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+struct NtStdinWorker { /* non-inherited */
+  volatile char sync;  /* spin sync start */
+  int refs;            /* reference count */
+  uint32_t tid;        /* of the worker */
+  int64_t reader;      /* the real handle */
+  int64_t writer;      /* for the worker */
+  int64_t worker;      /* thread handle */
+  int64_t consumer;    /* same as Fd::handle */
+  char16_t name[64];   /* for named pipe */
+};
+
+struct NtStdinWorker *NewNtStdinWorker(int) hidden;
+struct NtStdinWorker *RefNtStdinWorker(struct NtStdinWorker *) hidden;
+bool UnrefNtStdinWorker(struct NtStdinWorker *) hidden;
+void ForkNtStdinWorker(void) hidden;
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_SOCK_NTSTDIN_INTERNAL_H_ */