Eliminate some flakes

- Get ASAN working on Windows.

- Deleting directories and then recreating them with the same name in a
  short period of time appears to be a no-no on Windows.

- There's no reason to call FlushFileBuffers on close() for pipes, and
  it's harmful since it might block indefinitely for no good reason.

libc/sock/accept-nt.c

@@ -34,12 +34,13 @@ textwindows int accept$nt(struct Fd *fd, void *addr, uint32_t *addrsize,
   uint32_t yes;
   for (;;) {
     if (!WSAPoll(&(struct pollfd$nt){fd->handle, POLLIN}, 1, 1000)) continue;
-    if ((client = __getemptyfd()) == -1) return -1;
+    if ((client = __reservefd()) == -1) return -1;
     if ((h = WSAAccept(fd->handle, addr, (int32_t *)addrsize, 0, 0)) != -1) {
       if (flags & SOCK_NONBLOCK) {
         yes = 1;
         if (__ioctlsocket$nt(g_fds.p[client].handle, FIONBIO, &yes) == -1) {
           __closesocket$nt(g_fds.p[client].handle);
+          __releasefd(client);
           return __winsockerr();
         }
       }
@@ -48,6 +49,7 @@ textwindows int accept$nt(struct Fd *fd, void *addr, uint32_t *addrsize,
       g_fds.p[client].handle = h;
       return client;
     } else {
+      __releasefd(client);
       return __winsockerr();
     }
   }

libc/sock/epoll.c

@@ -1323,15 +1323,20 @@ static textwindows noinline int epoll_create1$nt(uint32_t flags) {
   int64_t ephnd;
   struct PortState *port_state;
   struct TsTreeNode *tree_node;
-  if ((fd = __getemptyfd()) == -1) return -1;
   if (wepoll_init() < 0) return -1;
+  if ((fd = __reservefd()) == -1) return -1;
   port_state = port_new(&ephnd);
-  if (!port_state) return -1;
+  if (!port_state) {
+    __releasefd(fd);
+    return -1;
+  }
   tree_node = port_state_to_handle_tree_node(port_state);
   if (ts_tree_add(&epoll__handle_tree, tree_node, (uintptr_t)ephnd) < 0) {
     /* This should never happen. */
     port_delete(port_state);
-    RETURN_SET_ERROR(-1, kNtErrorAlreadyExists);
+    err_set_win_error(kNtErrorAlreadyExists);
+    __releasefd(fd);
+    return -1;
   }
   g_fds.p[fd].kind = kFdEpoll;
   g_fds.p[fd].handle = ephnd;

libc/sock/kntwsadata.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/dce.h"
+#include "libc/nt/runtime.h"
 #include "libc/nt/winsock.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sock/internal.h"
@@ -32,15 +33,15 @@
  */
 hidden struct NtWsaData kNtWsaData;
 
-textwindows static void winsockfini(void) {
+static textwindows void winsockfini(void) {
   WSACleanup();
 }
 
-textwindows void winsockinit(void) {
+textwindows noasan void winsockinit(void) {
   int rc;
   atexit(winsockfini);
   if ((rc = WSAStartup(VERSION, &kNtWsaData)) != 0 ||
       kNtWsaData.wVersion != VERSION) {
-    abort();
+    ExitProcess(123);
   }
 }

libc/sock/socket-nt.c

@@ -29,7 +29,7 @@
 textwindows int socket$nt(int family, int type, int protocol) {
   int fd;
   uint32_t yes;
-  if ((fd = __getemptyfd()) == -1) return -1;
+  if ((fd = __reservefd()) == -1) return -1;
   if ((g_fds.p[fd].handle = WSASocket(family, type & ~(CLOEXEC | NONBLOCK),
                                       protocol, NULL, 0, 0)) != -1) {
     if (type & NONBLOCK) {