Dependancies needed to build the toolchain on Haiku

The first post-download build step launched by tool/tool_chain is to invoke "autogen"

However, autogen is not in HaikuPorts

So DL the source here:

• https://www.gnu.org/software/autogen/
• e.g. http://ftp.gnu.org/gnu/autogen/rel5.18.16/autogen-5.18.16.tar.gz

then xx