- Only reference the FOAM_EXT_LIBBIN locations when linking.
  The respective SCOTCH_ARCH_PATH/lib, METIS_ARCH_PATH/lib locations
  either do not exist, or are possibly inconsistent and won't be
  seen at run-time anyhow.

- Incorporate decompose/metisDecomp/Allwmake into the top-level
  decompose/Allwmake