openresty-valgrind deb package should not produce resty and restydoc sub-packages

[agentzh]

I've noted that the deb package openresty-valgrind currently produces the openresty-valgrind-resty and openresty-valgrind-restydoc sub-packages, which is not desired. Only the openresty package should produce the *-resty and *-restydoc sub-packages.