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/securitydescriptor.h

@@ -1,9 +1,8 @@
 #ifndef COSMOPOLITAN_LIBC_NT_STRUCT_SECURITYDESCRIPTOR_H_
 #define COSMOPOLITAN_LIBC_NT_STRUCT_SECURITYDESCRIPTOR_H_
+#include "libc/nt/struct/acl.h"
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 
-struct NtAcl;
-
 struct NtSecurityDescriptor {
   uint8_t Revision;
   uint8_t Sbz1;