Improve threading and i/o routines

- On Windows connect() can now be interrupted by a signal; connect() w/
  O_NONBLOCK will now raise EINPROGRESS; and connect() with SO_SNDTIMEO
  will raise ETIMEDOUT after the interval has elapsed.

- We now get the AcceptEx(), ConnectEx(), and TransmitFile() functions
  from the WIN32 API the officially blessed way, using WSAIoctl().

- Do nothing on Windows when fsync() is called on a directory handle.
  This was raising EACCES earlier becaues GENERIC_WRITE is required on
  the handle. It's possible to FlushFileBuffers() a directory handle if
  it's opened with write access but MSDN doesn't document what it does.
  If you have any idea, please let us know!

- Prefer manual reset event objects for read() and write() on Windows.

- Do some code cleanup on our dlmalloc customizations.

- Fix errno type error in Windows blocking routines.

- Make the futex polyfill simpler and faster.

libc/runtime/clone.c

@@ -30,7 +30,6 @@
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/atomic.h"
 #include "libc/intrin/describeflags.internal.h"
-#include "libc/intrin/strace.internal.h"
 #include "libc/intrin/ulock.h"
 #include "libc/intrin/weaken.h"
 #include "libc/limits.h"
@@ -667,7 +666,6 @@ errno_t clone(void *func, void *stk, size_t stksz, int flags, void *arg,
                         CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID)) !=
                  (CLONE_THREAD | CLONE_VM | CLONE_FS | CLONE_FILES |
                   CLONE_SIGHAND | CLONE_SYSVSEM)) {
-    STRACE("cosmo clone() is picky about flags, see clone.c");
     rc = EINVAL;
   } else if (IsXnu()) {
 #ifdef __x86_64__
@@ -695,8 +693,5 @@ errno_t clone(void *func, void *stk, size_t stksz, int flags, void *arg,
     rc = EAGAIN;
   }
 
-  STRACE("clone(%t, %p, %'zu, %#x, %p, %p, %p, %p) → %s", func, stk, stksz,
-         flags, arg, ptid, tls, ctid, DescribeErrno(rc));
-
   return rc;
 }