Merge branch 'fix-distclean' into 'master'

Fix make clean

Closes #231

See merge request redox-os/cookbook!520

clean.sh

@@ -12,5 +12,5 @@ fi
 
 for recipe_path in $recipes
 do
-    ./cook.sh "$recipe_path" distclean
+    IGNORE_ERROR=1 ./cook.sh "$recipe_path" distclean
 done

cook.sh

@@ -369,7 +369,8 @@ then
         do
             op "$recipe_name" "$i"
         done
-    else
+    elif [ "$IGNORE_ERROR" != "1" ]
+    then
         echo "cook.sh: recipe '$recipe_name' at not found" >&2
         exit 1
     fi