The script make/autoconf/configure should give a bit more output in case various errors occur (e.g. missing autoconf).
The new output in case of missing autoconf adds the PATH; additionally we show on AIX some info on how to install autoconf.

bash /jdk_6/jdk/jdk/configure
Runnable configure script is not present
...
Autoconf is not found on the PATH (/opt/freeware/bin:/usr/bin:/etc:/usr/sbin), and AUTOCONF is not set.
You need autoconf to be able to generate a runnable configure script.
You might be able to fix this by installing autoconf from the 'AIX Toolbox for Linux Applications' (or compile it from the sources).
Error: Cannot find autoconf