BPackageInfo: fix range check in c'tor
BPackageInfo::_ExtractUsers(): fix no group case
BuildSetup: remove obsolete dir variables
Add BDriverSettings to libbe_build
BRepositoryConfig::SetTo(): fix use after deallocation

The strings retrieved from the driver settings were used after
unload_driver_settings(). Use BDriverSettings which also simplifies
things quite a bit.
libsolv_build: add support for building on FreeBSD

Also fail immediately when an unsupported platform is encountered.
configure: set new variable HOST_SHA256

sha256sum and sha256 are detected.
Download*File rules: add optional source target

If specified the path to the source target can be used in the URL via
"$source".
Add rule ChecksumFileSHA256
Add build tool create_repository_config

Given a repository base URL and a repository info, it creates a
repository config file.
Adjust to changed HaikuPorts repository layout

The package kit actually requires the files "repo", "repo.info",
"repo.sha256" to be located under the repository base URL, so the
approach to name the repository file "repo-<hash>" doesn't work.
Now there's a directory "<hash>" which contains the files.

This commit moves the computation of the hash and downloading the
repository file from the build_haiku_image script to the jam build
system. The repo.info is also downloaded and a repository config file
is generated.
Copy repository config files to the image

... to common/settings/package-repositories. This way the used
repositories are already known to pkgman.