configure: bump automake requirement to 1.14 and autoconf to 2.69
configure: bump automake requirement to 1.14 and autoconf to 2.69

This is only required for builds from git, people can still
build tarballs if they only have older autotools.

https://bugzilla.gnome.org//show_bug.cgi?id=747624

shelsonjava/gstreamer,mparis/gstreamer,centricular/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,shelsonjava/gstreamer,krichter722/gstreamer,centricular/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,mparis/gstreamer,mparis/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,jpxiong/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,shelsonjava/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,centricular/gstreamer