- previously OpenFOAM library paths were set before adding in
  MPI-specific elements. However, this may mask some libraries.

  |  New library order  |  Old library order  |
  |---------------------|---------------------|
  |  user-lib (serial)  |  various 3rd-party  |
  |  site-lib (serial)  |  foam-lib (mpi)     |
  |  foam-lib (mpi)     |  ext-lib (mpi)      |
  |  foam-lib (serial)  |  system mpi-libs    |
  |  ext-lib  (mpi)     |  user-lib (serial)  |
  |  ext-lib  (serial)  |  site-lib (serial)  |
  |  various 3rd-party  |  foam-lib (serial)  |
  |  system mpi-libs    |  ext-lib (serial)   |
  |  dummy              |  dummy              |