build: Don't override the built-in RPM dependency generator

Four ocaml packages overrode RPM's dependency generator.
This upset some other packages that depended on them, when
not building in a clean mock environment.    RPM's builtin
dependency generator seems to be doing a fine job, so we don't
need this override.

Signed-off-by: Euan Harris <euan.harris@citrix.com>