Create a compiler wrapper for parcoach

Fixes #28 (closed).

This makes it easy to integrate parcoach in autotools/cmake projects; for instance for OSU it can be used the following way:

export OMPI_CXX=clang++-15
export OMPI_CC=clang-15
./configure CC="parcoach-wrapper mpicc" CXX="parcoach-wrapper mpicxx" LD=ld
make