PING: PR1176: Added --with-cacao-src-dir option

[Stefan Ring]

> Further to that, the one in the commit message is wrong as Stefan
> didn't write this:
>
> 2009-10-01  Robert Schuster  <robertschuster at fsfe.org>
>
>         * configure.ac: Added --with-cacao-src-dir option.
>         * acinclude: New macro AC_CHECK_WITH_CACAO_SRC_DIR.
>         * Makefile.am: Copy Cacao sources when USE_ALT_CACAO_SRC_DIR is used.

What do you want me to do exactly? Copy Robert's old changelog entry
over? It doesn't really fit, as the identifier got later renamed to
IT_WITH_CACAO_SRC_DIR after its original inclusion in icedtea6.