This commit updates $license variable in all APKBUILDs to comply with
short names specified by SPDX version 3.0 [1] where possible. It was
done using find-and-replace method on substrings inside $license
variables.

Only license names were updated, not "expressions" specifying relation
between the licenses (e.g. "X and Y", "X or Y", "X and (Y or Z)") or
exceptions (e.g. "X with exceptions").

Many licenses have a version or multiple variants, e.g. MPL-2.0,
BSD-2-Clause, BSD-3-Clause. However, $license in many aports do not
contain license version or variant. Since there's no way how to infer
this information just from abuild, it were left without the variant
suffix or version, i.e. non SPDX compliant.

GNU licenses (AGPL, GFDL, GPL, LGPL) are especially complicated. They
exist in two variants: -only (formerly e.g. GPL-2.0) and -or-later
(formerly e.g. GPL-2.0+). We did not systematically noted distinguish
between these variants, so GPL-2.0, GPL2, GPLv2 etc. may mean
GPL-2.0-only or GPL-2.0-or-later. Thus GNU licenses without "+" (e.g.
GPL2+) were left without the variant suffix, i.e. non SPDX compliant.

Note: This commit just fixes format of the license names, no
verification has been done if the specified license information is
actually correct!

[1]: https://spdx.org/licenses/

fixes #7510

There two main reasons for this change:

* Active support of PHP 5.x ended on January 2017, security support will
  end on December 2018. Packages in the main repository should be
  supported for at least 2 years, this means until first quarter of 2019
  for the upcoming v3.6.

* php7 and its extensions are currently in the community repository, so
  we can't use single abuild for both php5-* and php7-* packages (as we
  do for Python and Lua packages).

This change was suggested by @vakartel, approved by @ncopa, @kaniini, and
@jirutka.