Pass NINJAJOBS if N_PARALLEL is defined

Now that MAKEFLAGS is defined at the beginning of the scriptlet,
there is no need to pass MAKEFLAGS as an envar to the scriptlet.
But still NINJAJOBS is not defined. In most cases, when we want
to use all cores, this is not a problem. But if N_PARALLEL is
defined, it needs to be passed. Note that we also pass
MAKEFLAGS in this case, because we use the old "wrt_xxx" function,
but it is not used.

LFS/master.sh

@@ -131,18 +131,13 @@ chapter_targets() {       #
           *kernel*) ;; # No CFLAGS for kernel
           *)  wrt_optimize "$name" ;;
       esac
-      # MAKEFLAGS is set even if no optimization now.
-      # For new books, the scripts contain the MAKEFLAGS, so no
-      # need to set them in the envars except if binutils-pass1
-      # and REALSBU=y. For Old books, N_PARALLEL and JH_MAKEFLAGS
-      # are set and we must set the envars.
-      case "${mkf_included}${this_script}${REALSBU}" in
-          *binutils-pass1y)
-              wrt_makeflags "$name" "-j1" "1" ;;
-          n*)
-              wrt_makeflags "$name" "$JH_MAKEFLAGS" "$N_PARALLEL" ;;
-      esac
+      # There is no need to tweak MAKEFLAGS anymore, this is done
+      # by lfs.xsl. But still, NINJAJOBS needs to be set if
+      # N_PARALLEL is defined.
+      if [ -n "N_PARALLEL" ]; then
+         wrt_makeflags "$name" "$JH_MAKEFLAGS" "$N_PARALLEL"
       fi
+    fi # end of package specific instructions
 
 # Some scriptlet have a special treatment; otherwise standard
     case "${this_script}" in
@@ -260,14 +255,6 @@ build_Makefile() {           #
 #  echo nb_chaps: $nb_chaps
 # end DEBUG
 
-  # We need to know if we have an old or a new book (with included MAKEFLAGS)
-  # we grep for MAKEFLAGS in chapter04 to find out.
-  if grep -q MAKEFLAGS chapter04/*; then
-	  mkf_included=y
-  else
-	  mkf_included=n
-  fi
-
   # Make a temporary file with all script targets
   for (( i = 4; i < nb_chaps+4; i++ )); do
     chapter_targets $i