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/ntaccesscheck.c

@@ -81,7 +81,7 @@ textwindows int ntaccesscheck(const char16_t *pathname, uint32_t flags) {
       (result || flags == F_OK)) {
     rc = 0;
   } else {
-    rc = winerr();
+    rc = __winerr();
   }
   close(hImpersonatedToken);
   close(hToken);