In general, use this:
@for dir in $(SUBDIRS) ; do \
if [ -d $$dir ] ; then \
(cd $$dir && $(MAKE)) || exit 1; \
fi \
done
Basically, silently skip missing subdirs but generate an error and stop if
there's a compilation or install problem.
This was done inconsistantly before. In once case, a missing subdir was
causing us to go into an infinte loop!
