Apache default version -> 2.4

[coypu%SDF.ORG@localhost]

Hello, a heads up,

I've changed the default apache version to apache24.
You could use both before and still can, but it defaulted to 22.

If you are using defaults and would like to keep using apache22, just
add PKG_APACHE_DEFAULT=apache22 to your /etc/mk.conf

This is a commit to pkgsrc-current and does not affect pkgsrc-2016Q4.
It will affect 2017Q1.