optimize_functions: change wrt_makeflags parameters

In order to be able to pass NINJAJOBS=1 when optimize is 0, we
add two paramters to this function. The three parameters are
then:
- the name of the package (tested against opt_override)
- MAKEFLAGS for this package
- NINJAJOBS for this package

optimize/optimize_functions

@@ -70,19 +70,18 @@ EOF
 wrt_makeflags() {                  # Apply MAKEFLAGS to build
 #----------------------------------#
   local pkg=$1
-  local MKF
+  local MKF=$2
+  local NJJ=$3
 
   if [[ "$BLACK_LIST" =~ ${pkg} ]]; then
-    MKF=unset
+    MKF="-j1"
-  else
+    NJJ="1"
-    MKF=$JH_MAKEFLAGS
   fi
 
-  if [[ "$MKF" != "unset" ]]; then
 (
 cat << EOF
-	@echo "export MAKEFLAGS=\"$JH_MAKEFLAGS\"" >> envars
+	@echo "export MAKEFLAGS=\"$MKF\"" >> envars
+	@echo "export NINJAJOBS=\"$NJJ\"" >> envars
 EOF
 ) >> $MKFILE.tmp
-  fi
 }