Improve RPATH handing in CoreNeuron/ReportingLib

Latest build has failure message :

-- Installing: /gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/coreneuron-perfmodels-mlhhm5l6a4xbeldue4xktrpfem55r7um/lib64/libcoreneuron.a
-- Installing: /gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/coreneuron-perfmodels-mlhhm5l6a4xbeldue4xktrpfem55r7um/bin/coreneuron_exec
CMake Error at apps/cmake_install.cmake:53 (file):
  file RPATH_CHANGE could not write new RPATH:

    /gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/coreneuron-perfmodels-mlhhm5l6a4xbeldue4xktrpfem55r7um/lib:/gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/coreneuron-perfmodels-mlhhm5l6a4xbeldue4xktrpfem55r7um/lib64:/bgsys/drivers/ppcfloor/comm/xl/lib:/gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/neurodamus-develop-ysvskstb7enjybby3lkg6wccb2f75n3q/lib:/gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/reportinglib-develop-egg74axinani2dbxeth6zm2w54h4uvjs/lib64

  to the file:

    /gpfs/bbp.cscs.ch/scratch/gss/bgq/kumbhar/SPACK_INSTALLS/SPACK_BBP_PREFIX/bg/install/2017_08_27_22_12/bgq-cnk-ppc64/xl-12.1/coreneuron-perfmodels-mlhhm5l6a4xbeldue4xktrpfem55r7um/bin/coreneuron_exec

  No valid ELF RPATH or RUNPATH entry exists in the file;
Call Stack (most recent call first):
  cmake_install.cmake:38 (include)

make: *** [install] Error 1
==> Executing phase : 'install'
++ spack find coreneuron@perfmodels +mpi %xl '^mpich'

ReportingLib and CoreNEURON cmake needs to be revisited.

BlueBrain / spack-packages

Improve RPATH handing in CoreNeuron/ReportingLib #19