ENH: relocate 3rd party libraries -> FOAM_EXT_LIBBIN

- place under $WM_THIRD_PARTY_DIR/lib/$WM_OPTIONS
- relocate FOAM_MPI_LIBBIN accordingly

Allwmake

@@ -8,6 +8,12 @@ wmakeCheckPwd "$WM_PROJECT_DIR" || {
     exit 1
 }
 
+[ -n "$FOAM_EXT_LIBBIN" ] || {
+    echo "Error: FOAM_EXT_LIBBIN not set"
+    echo "    Check the OpenFOAM entries in your dot-files and source them."
+    exit 1
+}
+
 # wmake is required for subsequent targets
 ( cd wmake/src && make )