Implement getaddrinfo in wasi_socket_ext.c (#1413)

So getaddrinfo() can be used when compiling wasm app of C programs.

samples/socket-api/wasm-src/CMakeLists.txt

@@ -79,3 +79,4 @@ endfunction()
 compile_with_clang(tcp_server.c)
 compile_with_clang(tcp_client.c)
 compile_with_clang(send_recv.c)
+compile_with_clang(addr_resolve.c)

samples/socket-api/wasm-src/addr_resolve.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2022 Amazon.com, Inc. or its affiliates. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef __wasi__
+#include <wasi_socket_ext.h>
+#else
+#include <netdb.h>
+#endif
+
+int
+lookup_host(const char *host)
+{
+    struct addrinfo hints, *res, *result;
+    int errcode;
+    char addrstr[100];
+    void *ptr;
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+
+    errcode = getaddrinfo(host, NULL, &hints, &result);
+    if (errcode != 0) {
+        perror("getaddrinfo");
+        return -1;
+    }
+
+    res = result;
+
+    printf("Host: %s\n", host);
+    while (res) {
+        switch (res->ai_family) {
+            case AF_INET:
+                ptr = &((struct sockaddr_in *)res->ai_addr)->sin_addr;
+                break;
+            case AF_INET6:
+                ptr = &((struct sockaddr_in6 *)res->ai_addr)->sin6_addr;
+                break;
+            default:
+                printf("Unsupported address family: %d\n", res->ai_family);
+                continue;
+        }
+        inet_ntop(res->ai_family, ptr, addrstr, 100);
+        printf("IPv%d address: %s (%s)\n", res->ai_family == AF_INET6 ? 6 : 4,
+               addrstr, res->ai_socktype == SOCK_STREAM ? "TCP" : "UDP");
+        res = res->ai_next;
+    }
+
+    freeaddrinfo(result);
+
+    return EXIT_SUCCESS;
+}
+
+int
+main(int argc, char *argv[])
+{
+    if (argc < 2) {
+        printf("Usage: %s DOMAIN\n", argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    return lookup_host(argv[1]);
+}