[wmlunits] use scons as cmake seems broken right now

data/tools/unit_tree/update-wmlunits

@@ -40,8 +40,7 @@ rm -rf $TEMP/*
 
 # we only need the parser, but have to build the game executable for that
 echo BUILDING
-make -C $BUILD wesnoth > /dev/null 2>&1 || true
-make -C $BUILD mo-update > /dev/null 2>&1
+TRAVIS=1 TRAVIS_OS_NAME=Linux scons -Y "$SRC" --option-cache="$BUILD/.scons-option-cache"
 
 # later can just rebuild updated campaigns, but for now rebuild everything
 rm -f $DIR/overview.txt