vl: fix resource leak with monitor_fdset_add_fd

monitor_fdset_add_fd returns an AddfdInfo struct (used by the QMP
command add_fd).  Free it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

vl.c

@@ -1012,6 +1012,7 @@ static int parse_add_fd(QemuOpts *opts, void *opaque)
     int fd, dupfd, flags;
     int64_t fdset_id;
     const char *fd_opaque = NULL;
+    AddfdInfo *fdinfo;
 
     fd = qemu_opt_get_number(opts, "fd", -1);
     fdset_id = qemu_opt_get_number(opts, "set", -1);
@@ -1061,8 +1062,9 @@ static int parse_add_fd(QemuOpts *opts, void *opaque)
     }
 
     /* add the duplicate fd, and optionally the opaque string, to the fd set */
-    monitor_fdset_add_fd(dupfd, true, fdset_id, fd_opaque ? true : false,
-                         fd_opaque, NULL);
+    fdinfo = monitor_fdset_add_fd(dupfd, true, fdset_id, !!fd_opaque, fd_opaque,
+                                  &error_abort);
+    g_free(fdinfo);
 
     return 0;
 }