dev-lang/php: revision the 5.6.x and 7.x series to use upstream php-fpm.conf.

dev-lang/php: revision the 5.6.x and 7.x series to use upstream php-fpm.conf.

There are a few changes batched together here.

The main purpose of the new revisions is to stop using our bundled
php-fpm.conf (from php-5.3) and switch to the one provided by
upstream. This is bug 559116. In the 5.6.x series, this is trivial: we
just install the php-fpm.conf from the tarball. But in 7.x, upstream
has split the FPM config into pieces. Their default "include" path
needed to be changed for our slotting, so that has been done with a
`sed` in src_prepare().  We then install the split "www.conf" config
file in the location that was enshrined with `sed`.

Next, the autotools-utils eclass was dropped. The functionality from
src_configure() was inlined. This is due to the deprecation of that
eclass; see,

  https://blogs.gentoo.org/mgorny/2015/11/13/the-ultimate-guide-to-eapi-6/

Finally, the db-use eclass was dropped. It was no longer used.

Gentoo-Bug: 559116

Package-Manager: portage-2.2.20.1