depends zip &&

optional_depends nspr \
                 "--with-system-nspr" \
                 "--without-system-nspr" \
                 "to use system NSPR library" &&

optional_depends valgrind \
                 "--enable-valgrind" \
                 "--disable-valgrind" \
                 "to enable Valgrind integration hooks" &&

optional_depends readline \
                 "--enable-readline" \
                 "--disable-readline" \
                 "for linking js shell to system readline library"

.