* Bison 2.0 or newer.
+ Recommended.
- Needed if you use the 'getdate' module.
+ Needed if you use the 'parse-datetime' module.
+ Homepage:
http://www.gnu.org/software/bison/
+ Download:
* GNU libtool 1.5.22 or newer.
+ Optional.
Needed if you want to invoke gnulib-tool with option --libtool.
+ libtool 2.2.x or newer is needed if you want to invoke gnulib-tool
+ with options --create-testdir/--test and --libtool.
+ Homepage:
http://www.gnu.org/software/libtool/
+ Download: