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/

This reverts commit f72f37cc.

So that it can be used as a stand-alone command line spell checker

Since abuild v2.22.0, these are removed automatically unless 'libtool'
option has been specified.

for musl build. the changes are automatically done based on previous
build log errors, so this does not guarantee successful build, but
is a required.

ref #501

ref #384