qibuild: new host-package

qiBuild is a cross-platform build system for corss-compilation. It is
based on CMake and python.

The qiBuild CMake framework can be used as a standalone CMake extension,
which does not require anything else, nit even the qiBuild python tools.

The qiBuild python part provides a bunch of tools handling sources,
toolchains and builds.

So, this qibuild package only does not depend on python since only the
CMake extension will be used.
pkg-cmake.mk: update the target description in the toolchainfile.cmake
openni: new package

Presently, OpenNI:
* does not build against uclibc, since it uses aio.h;
* only support arm and x86/x86_64 processors

Current version is based on the 1.5.2.23 stable release.
primesense-sensor: new package
opencv: add openni/primesense sensor support