This changes our approach from having independent tarballs to
having a single, monolithic tarball for all of the libraries

Right now, the pkg-config checks for the system version of
libdhash are forcibly disabled, requiring the SSSD to build it
from its own tree. In the future, when we split the libraries off
from the SSSD, it will be easy to switch this check to the
external library.

Previously we were only building them but not running them.

Necessary for RPM builds on RHEL5

Previously, only the SSSD server components were being built with
compile-time warnings enabled. This patch will ensure that all
components in common and sss_client are also built the same way.

LT_INIT is supported only on Libtool >= 2.0, so I reverted it to
using AC_PROG_LIBTOOL.

Also reorganized how the common libraries were being built. Now
they are treated as libtool convenience libraries instead of
installable libraries (the --with-singlelib configure flag can
still be used to generate a combined, installable DSO)

I cleaned up the set of files being installed by automake, so the
list of things we need to remove before packaging the RPM is now
only the .la files associated with our own plugins.

Allow configuration and build of individual SSSD utility libraries
from their own subdirectories. Building all utilities is still
possible recursively from the common root.