x86_64 is used as a baseline: the "x86_64" entry, whatever status it has,
is transformed into "all", and then the other entries in ARCHITECTURES
either dropped or rearranged appropriately.
* Add PATCH() to use Haiku-style directories instead of the defaults:
/usr/local/etc/ccache.conf => /boot/system/settings/ccache.conf
$HOME/.ccache/ccache.conf => /home/config/cache/ccache/ccache.conf
$HOME/.ccache/ => /home/config/cache/ccache/
/usr/local/bin/ => /boot/home/config/non-packaged/bin/
* Create [/boot/system/]settings/ccache.conf as the system-wide
configuration file with the "keep-old" label.
* Pass "`finddir B_SYSTEM_SETTINGS_DIRECTORY`" as sysconfdir in order
to have the short path displayed instead of the long one, in case
the system-wide configuration file contains errors.
* Referring the current haiku version explicitly is not needed, since
the RequiresUpdater takes care of setting the version of Haiku used
for building a package.