Downgrade to the (released) version of autoconf 2.69
Downgrade to the (released) version of autoconf 2.69

When commit 4750e1b655 was made, the configure script was generated with
a version of autoconf (also confusingly marketed as 2.69) that's
unreleased. This commit reverts back to the released version of 2.69.

Co-authored-by: Chris Hajas <e8e414b713ceee89684f46616039fe9bed26bfcc@pivotal.io>
Co-authored-by: Jesse Zhang <58cb4a1fad2c21afe8ba00106a15922c2987b6b3@gmail.com>

greenplum-db/gpdb,jmcatamney/gpdb,xinzweb/gpdb,lisakowen/gpdb,ashwinstar/gpdb,xinzweb/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,lisakowen/gpdb,xinzweb/gpdb,lisakowen/gpdb,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,adam8157/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,50wu/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,lisakowen/gpdb,50wu/gpdb,ashwinstar/gpdb,lisakowen/gpdb,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,xinzweb/gpdb,adam8157/gpdb,50wu/gpdb,adam8157/gpdb,jmcatamney/gpdb,adam8157/gpdb,greenplum-db/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,greenplum-db/gpdb,lisakowen/gpdb,greenplum-db/gpdb,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,50wu/gpdb,ashwinstar/gpdb