functions: add new helpers that create a dir and cd/pushd into it

A lot of places are currently doing:
mkdir -p foo/bar
cd foo/bar

Or even:
mkdir -p foo/bar
pushd foo/bar
[...]
popd

Provide both wrapper to ease doing this.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

python

import sys

sys.path.insert(0, '@@PREFIX@@/share/gcc-@@VERSION@@/python')

from libstdcxx.v6.printers import register_libstdcxx_printers

register_libstdcxx_printers (None)

end