* HaikuRepository rule: Create the repository config.
* HaikuImage: Add the repository config for the Haiku image. The
repository cache is not added, though (it would only be available, if
the repository had been built before).
Implements #10287. The Haiku repository is now available in Haiku by
default.
* PreprocessPackageInfo rule: Pull out new rule
PreprocessPackageOrRepositoryInfo which does the sed substituation and
optionally the filtering through the C preprocessor.
* HaikuRepository rule: Generate the repository info file (from the
given template). No longer do that in the build_haiku_repository
script.
* Add rule HaikuRepository to build a repository from a repository info
file and a list of package files. It calls a build_haiku_repository
script which does all the work.
* Add target <repository>haiku for building the Haiku package
repository.
It should be built via "jam -q @alpha-raw build <repository>haiku";
the build profile is only needed to activate all build features.
