microperl: bump to version 5.12.4 and convert to gentargets

* Convert microperl to gentargets infrastructure
* Bump to a more modern version 5.12.4
* Introduce the bundle options to simplify people's lives

host-microperl is a fully-fledged perl.

For the time being we can't build XS modules thus breaking
target automake support for example since it requires IO.

target-automake was broken before anyway since the automake version
bump.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>