Add target for building a Haiku package repository

* 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.

build/jam/repositories/Haiku

@@ -0,0 +1,23 @@
+# Builds the Haiku packages repository.
+
+local haikuRepository = <repository>haiku ;
+MakeLocate $(haikuRepository)
+	: $(HAIKU_PACKAGE_REPOSITORIES_DIR_$(HAIKU_PACKAGING_ARCH)) ;
+
+local repoInfo = <repository-info>haiku ;
+SEARCH on $(repoInfo) = $(HAIKU_TOP)/src/data/repository_infos ;
+
+local secondaryArchs = $(TARGET_PACKAGING_ARCHS[2-]) ;
+local packages =
+	haiku
+	haiku_devel
+	haiku_loader
+	haiku_userguide
+	haiku_welcome
+	makefile_engine
+
+	haiku_$(secondaryArchs)
+	haiku_$(secondaryArchs)_devel
+	;
+
+HaikuRepository $(haikuRepository) : $(repoInfo) : $(packages:S=.hpkg) ;