* Add rule FSplitPackageName. It splits a package name into port name
and package suffix.
* FSetConditionsHold: Rename to FConditionsHold and replace the set
parameter by a predicate rule parameter, thus adding more flexibility.
* FIsBuildFeatureEnabled: Use the faster check.
* Add rule FQualifiedBuildFeatureName. Given a build feature name, it
prepends the current packaging architecture to yield a qualified
feature name. Is used by the other build feature rules so that the
same build feature can be configured differently for each arch.
* ExtractBuildFeatureArchives: The supplied list is now filtered via
FFilterByBuildFeatures, allowing for build feature conditions in the
list.
* Add rule InitArchitectureBuildFeatures. It is called early for each
configured architecture, setting up some basic build features for it.
"primary" is set for the primary architecture and a "secondary_<arch>"
is set for each secondary architecture.
* BuildFeatures: Add secondary architecture support: Use the correct
paths for libraries and headers (subdir for secondary architecture)
and configure the icu and zlib sources only for the primary
architecture.
* BootstrapPackageRepository: The package lists are now filtered via
FFilterByBuildFeatures, allowing for build feature conditions in the
lists.
* IsPackageAvailable, FetchPackage: Add secondary architecture support.
* HaikuPortsCross/x86_gcc2: Add icu and zlib x86 secondary packages.
The second stage Haiku cross devel package for the secondary
architecture can now be built.
