Add epoll and do more release readiness changes

This change also pays off some of the remaining technical debt with
stdio, file descriptors, and memory managemnt polyfills.

libc/nt/struct/afd.h

@@ -0,0 +1,22 @@
+#ifndef COSMOPOLITAN_LIBC_NT_STRUCT_AFD_H_
+#define COSMOPOLITAN_LIBC_NT_STRUCT_AFD_H_
+#include "libc/nt/enum/status.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+struct NtAfdPollHandleInfo {
+  int64_t Handle;
+  uint32_t Events;
+  NtStatus Status;
+};
+
+struct NtAfdPollInfo {
+  int64_t Timeout;
+  uint32_t NumberOfHandles;
+  uint32_t Exclusive;
+  struct NtAfdPollHandleInfo Handles[1];
+};
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_NT_STRUCT_AFD_H_ */