there's no nice syscall to manipulate xattrs with atfd and
or open the symlink without dereferencing it (and having fd
that we can do xattrs with)

user xattrs on tmpfs are not supported no non-grsec kernels,
and many times root fs is mounted without user_xattr. Thus
to allow things to go smoothly on non-grsec kernels xattr
unsupported errors are now hidden.

xattrs can be fixed still now with "apk fix --xattrs"

use ERR_PTR mechanism, and handle it at all places.

on arm char is by default unsigned, so this caused crashes
as the ERR_PTR mechanism did not work as expected with unsigned
types. extend the array type to be signed short explicitly.

fixes #4040

issue cought by fortify

apk in alpine 3.1 already supports this optimization, but kept
the database format. now is time to start using this feature.

ref #3027

fixes #4040

fixes #4019

ref #3027

ref #3027

Package pinning was first implemented with 'p' tag. However, it
was before any release renamed to 's', and 'p' was reserved for
package provides support for which is used now.

fixes #3840

this makes 'lbu diff' and aaudit diffs nice when a world
dependency is added or removed. sorting also makes the ordering
more deterministic as the world targets constraints are always
applied in the same order. test suite updated accordingly.

using space was for backwards compatibility with apk-tools 2.2.2
and earlier (from January 2012)

the location changed in apk-tools 2.1.0 (March 2011) which was
used in Alpine Linux 2.2.

when removing large sets of packets, the ordering of removal
was not quaranteed to honor dependencies. this fixes the removal
order to be in reverse dependency order as far as possible.

In case all applet arguments are packages names (that is are not
including wildcards), return error if they do not match to some
package.

Allows running apk as an unprivileged user, e.g. with fakeroot.
Opening the lock file fails without the write permission.

there are only few combinations for that triplet, and they
occur multiple times reducing the struct sizes a bit. make
sane defaults and prepare to not write defaults to disk
to reduce on-disk installed db size.

Add also a new 'commit' group that is the common options
for all applets that can commit package changes.