- added AC_PROG_CXX to various configure scripts and have the result substituted
    certain packages
  - removed the cxx package in eli
  - added Makefile.in for odin
  - added compilation support of C++ in the cc package
  - removed overwriting the compiler in toolmk.h
  - changed script to generate Makefiles

This was needed due to different ABIs between C++ and C. It is not possible to compile
some C-files with gcc and then one or two C++-files with g++ and the be able to link
these into the same executable.

The result now is that, whenever at least one C++-file (*.cc, *.cxx, *.CC, etc) is
must be compiled for the resulting program or library, then all files will be compiled
using the given compiler for C++.