README: update a list of build deps for rpm-based systems

A list of build dependencies for rpm-based OSes is missing a few items.
This fills in the gaps.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Merge pull request #883 from idryomov/wip-readme

README: update a list of build deps for rpm-based systems

Reviewed-by: Sage Weil <sage@inktank.com>