'false' and 'true' are not built-ins on most compilers.

Use TRUE/FALSE from setup_once.h.

lib/ftp.c

@@ -1888,11 +1888,11 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
     break;
   case CURLPROXY_SOCKS4:
     result = Curl_SOCKS4(conn->proxyuser, newhost, newport,
-                         SECONDARYSOCKET, conn, false);
+                         SECONDARYSOCKET, conn, FALSE);
     break;
   case CURLPROXY_SOCKS4A:
     result = Curl_SOCKS4(conn->proxyuser, newhost, newport,
-                         SECONDARYSOCKET, conn, true);
+                         SECONDARYSOCKET, conn, TRUE);
     break;
   default:
     failf(data, "unknown proxytype option given");

lib/url.c

@@ -2644,11 +2644,11 @@ static CURLcode ConnectPlease(struct SessionHandle *data,
         break;
       case CURLPROXY_SOCKS4:
         result = Curl_SOCKS4(conn->proxyuser, conn->host.name,
-                             conn->remote_port, FIRSTSOCKET, conn, false);
+                             conn->remote_port, FIRSTSOCKET, conn, FALSE);
         break;
       case CURLPROXY_SOCKS4A:
         result = Curl_SOCKS4(conn->proxyuser, conn->host.name,
-                             conn->remote_port, FIRSTSOCKET, conn, true);
+                             conn->remote_port, FIRSTSOCKET, conn, TRUE);
         break;
       default:
         failf(data, "unknown proxytype option given");