Add target build possibility

[Dreaded-Gnu]

Currently only host tools and libraries can be built with the host multilib build.

To prepare for building the base of the whole system root by building all necessary libraries for a target platform, the new python script needs to be extended by parameter --target. The target parameter shall be used to lookup the compilation settings like used cpu, mode, float and add a temporary overwrite of the out prefix for all so called target packages