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/calls/ioctl-default.c

@@ -29,13 +29,13 @@ int ioctl$default(int fd, uint64_t request, void *memory) {
   int64_t handle;
   if (!IsWindows()) {
     return ioctl$sysv(fd, request, memory);
-  } else if (isfdopen(fd)) {
+  } else if (__isfdopen(fd)) {
     if (g_fds.p[fd].kind == kFdSocket) {
       handle = g_fds.p[fd].handle;
       if ((rc = weaken(__ioctlsocket$nt)(handle, request, memory)) != -1) {
         return rc;
       } else {
-        return weaken(winsockerr)();
+        return weaken(__winsockerr)();
       }
     } else {
       return eopnotsupp();