update autoconf to at least 2.69 for aarch64 support

Submitted by Kevin Fenzi

Assigned to Peter de Ridder

Link to original bug (#9942)

Description

Downstream bug:

https://bugzilla.redhat.com/show_bug.cgi?id=926631

The currently used autoconf version in thunar-vfs is too old to support aarch64, so it cannot build on those platforms. Please update before next release if possible.