In order to avoid conflicts between the LRDE bison version needed to
build nolimips and the last bison version installed on the host machine,
this commit gets bison from the LRDE tarball, builds it and uses it.

This commit fixes also some ugly tabulations and trailing whitespaces.

* .gitignore,
* bootstrap,
* build-aux/bin/bison++.in,
* build-aux/gitlog-to-changelog,
* configure.ac: here.