COMP: drop FOAM_EXT_LIBBIN dependency for VTK-related items

- they don't use scotch/metis anyhow, which are the only things
  placed in FOAM_EXT_LIBBIN

src/paraview-plugins/PVFoamReader/PVFoamReader/CMakeLists.txt

@@ -7,7 +7,6 @@ include(${PARAVIEW_USE_FILE})
 
 link_directories(
     $ENV{FOAM_LIBBIN}
-    $ENV{FOAM_EXT_LIBBIN}
 )
 
 include_directories(

src/paraview-plugins/PVblockMeshReader/PVblockMeshReader/CMakeLists.txt

@@ -7,7 +7,6 @@ include(${PARAVIEW_USE_FILE})
 
 link_directories(
     $ENV{FOAM_LIBBIN}
-    $ENV{FOAM_EXT_LIBBIN}
 )
 
 include_directories(

src/runTimePostProcessing/CMakeLists-Common.txt

@@ -21,7 +21,6 @@ include_directories(
 
 link_directories(
     $ENV{FOAM_LIBBIN}
-    $ENV{FOAM_EXT_LIBBIN}
 )
 
 add_definitions(