RFR: 8023957: Lock down version of autoconf

[Tim Bell]

Erik:

> Following the discussion about the autoconf version, here is a patch 
> that changes the AC_PREREQ macro to require at least 2.69. For now, 
> since there are no newer versions, this will make us require version 
> 2.69. I also removed the workaround for getting 2.67 that was put into 
> autogen.sh.
>
> http://cr.openjdk.java.net/~erikj/8023957/webrev.root.01/

Looks good to me as well.

Tim