[SSSD] [PATCH] Split the providers into separate subpackages

[Jakub Hrozek]

Hi,

the attached patch splits the previously monolithic sssd package into
sssd-common that contains the deamon and the responders and per-provider
packages such as sssd-ldap or sssd-ipa.

This split would benefit two parties:
    1) security auditors who are often trying to find the smallest package
    set including dependencies needed for the package to function. They
    would be able to i.e. install sssd-ldap and not bother about
    sssd-ipa or sssd-ad pulling in more dependencies.
    2) 3rd party programs such as realmd or authconfig that would only
    be able to require or install on demand the needed packages.

The patch addresses https://fedorahosted.org/sssd/ticket/1510 and must b
applied on the two specfile patches I sent earlier (the thread subject
included libsss_sudo).