erp5.util[testnode] is going to replace functionality of
slapos.recipe.erp5testnode.

this option was making git unusable behind a proxy

"gzip" is undefined. Not working stuff should not be in master
branch, so revert this work.
This reverts commit dcc93a3b.

Without this, system perl will be used.

Required by maatkit.

According to commit log libpng12 section was not needed, but was refered here.