Revert "fix a bug which simulator use high CPU usage if app cannot respond"

This change made normal usage of the REPL when trying to select a view
very slow. Needs a better fix after the 2.25 release.

This reverts commit 5b1398c796.

Related to http://hipbyte.myjetbrains.com/youtrack/issue/RM-458.

bin/sim.m

@@ -712,18 +712,6 @@ receive_string(void)
     NSMutableString *res = [NSMutableString new];
     bool received_something = false;
     while (true) {
-	fd_set read_fds;
-	FD_ZERO(&read_fds);
-	FD_SET(repl_fd, &read_fds);
-
-	struct timeval tv;
-	tv.tv_sec = 0;
-	tv.tv_usec = 50000;
-	if (select(repl_fd + 1, &read_fds, NULL, NULL, &tv) == -1) {
-	    perror("select()");
-	    break;
-	}
-
 	char buf[1024 + 1];
 	ssize_t len = recv(repl_fd, buf, sizeof buf, 0);
 	if (len == -1) {