COMP: make libscotch/libptscotch targets instead of scotch/ptscotch

- we do not generally need any of executables, just the libraries.
  This also avoids generating a libscotchmetis too.

Allwmake

@@ -158,7 +158,7 @@ then
     [ -n "$I_MPI_CC" ] || export I_MPI_CC="$(whichCC)"
 
     make realclean 2>/dev/null  # Extra safety
-    make -j $WM_NCOMPPROCS scotch \
+    make -j $WM_NCOMPPROCS libscotch \
      && make \
         prefix=$prefixDIR \
         includedir=$incDIR \
@@ -235,7 +235,7 @@ then
         [ -n "$I_MPI_CC" ] || export I_MPI_CC="$(whichCC)"
 
         make realclean 2>/dev/null  # Extra safety
-        make -j $WM_NCOMPPROCS ptscotch \
+        make -j $WM_NCOMPPROCS libptscotch \
          && make \
             prefix=$prefixDIR \
             includedir=$incDIR \