Update __wasi_sock_accept signature to match wasi_snapshot_preview1 (#1531)

The function was introduced to WASI about half a year ago after it already
existed in WAMR.

It caused problems with compiling `wasi_socket_ext.c` with the wasi-sdk
that already had this hostcall exported (wasi-sdk >= 15).

The approach we take is the following:
- we update WASI interface to be compatible with the wasi_snapshot_preview1
- compilation with `wasi_socket_ext.c` supports both wasi_sdk >= 15 and wasi_sdk < 15
  (although we intend to drop support for < 15 at one point of time)
- we override `accept()` from wasi-libc - we do that because `accept()` in `wasi-libc`
  doesn't support returning address (as it doesn't have `getpeername()` implemented),
  so `wasi_socket_ext.c` offers more functionality right now

Resolves #1167 and #1528.

[1] https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/witx/wasi_snapshot_preview1.witx

core/iwasm/libraries/lib-socket/inc/wasi_socket_ext.h

@@ -140,8 +140,10 @@ struct addrinfo {
     struct addrinfo *ai_next; /* Pointer to next in list.  */
 };
 
+#ifndef __WASI_RIGHTS_SOCK_ACCEPT
 int
 accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);
+#endif
 
 int
 bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
@@ -191,21 +193,30 @@ void
 freeaddrinfo(struct addrinfo *res);
 #endif
 
+/**
+ * __wasi_sock_accept was introduced in wasi-sdk v15. To
+ * temporarily maintain backward compatibility with the old
+ * wasi-sdk, we explicitly add that implementation here so it works
+ * with older versions of the SDK.
+ */
+#ifndef __WASI_RIGHTS_SOCK_ACCEPT
 /**
  * Accept a connection on a socket
  * Note: This is similar to `accept`
  */
 int32_t
-__imported_wasi_snapshot_preview1_sock_accept(int32_t arg0, int32_t arg1)
+__imported_wasi_snapshot_preview1_sock_accept(int32_t arg0, int32_t arg1,
+                                              int32_t arg2)
     __attribute__((__import_module__("wasi_snapshot_preview1"),
                    __import_name__("sock_accept")));
 
 static inline __wasi_errno_t
-__wasi_sock_accept(__wasi_fd_t fd, __wasi_fd_t *fd_new)
+__wasi_sock_accept(__wasi_fd_t fd, __wasi_fdflags_t flags, __wasi_fd_t *fd_new)
 {
     return (__wasi_errno_t)__imported_wasi_snapshot_preview1_sock_accept(
-        (int32_t)fd, (int32_t)fd_new);
+        (int32_t)fd, (int32_t)flags, (int32_t)fd_new);
 }
+#endif
 
 /**
  * Returns the local address to which the socket is bound.

core/iwasm/libraries/lib-socket/src/wasi/wasi_socket_ext.c

@@ -140,7 +140,7 @@ accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
     __wasi_fd_t new_sockfd;
     __wasi_errno_t error;
 
-    error = __wasi_sock_accept(sockfd, &new_sockfd);
+    error = __wasi_sock_accept(sockfd, 0, &new_sockfd);
     HANDLE_ERROR(error)
 
     error = getpeername(new_sockfd, addr, addrlen);