Build and install libafsauthent.so.2

During the libtool interim, we had been building a .0 but not
installing it.  Prior to the libtoolization of shlibafsauthent, we
had installed a libafsauthent.so.1.1.  The use of libtool is a major
shift, and no one has been explicitly tracking for incompatible
changes in the interim, so it seems prudent to bump the SONAME
for the new stable branch on general principles.

At time of this writing, the libtool rules for updating the
version information is found at:
http://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
and
http://www.gnu.org/software/libtool/manual/html_node/Libtool-versioning.html

This lets us consolidate the building of the shared and static libafsrpc
and their installation), as libtool will happily do both for us
at once.

We explicitly do not install the .la files, as our libtool use is
to be kept entirely internal.

Change-Id: I283f9bb74eb9853c268e8642ac1f01741deeae2b
Build a usable pam_afs.so

Our use of libtool for building the pam modules resulted in shared
objects which had dependencies on liboafs_auth.so and liboafs_kauth.so,
neither of which are installed.

We still need some way to resolve those dependencies at link time, and
a dependency on libafsauthent.so seems ill-advised to insert into the
pam stack, so we are left with only the option of directly linking in
the requisite functionality.  Fortunately, almost all of the requisite
convenience libraries of PIC objects already exist to meet the
requirements of libafsrpc and libafsauthent; the only exception is
from the auth module.  Here, we require a new convenience library,
because the pam_afs.krb.so module includes its own version of ktc.o,
compiled with AFS_KERBEROS_ENV defined, yet the pam_afs.so module
requiers a ktc.o compiled without AFS_KERBEROS_ENV defined.  The
convenience library from the auth module can only include one version,
and would therefore be wrong for the other.  As such, create the new
libpam_auth.la archive from the BASE_objs in src/auth, and manually
compile ktc.lo and ktc_krb.lo as needed for the pam modules.

As for libafsrpc and libafsauthent, the convenience libraries included
from other parts of the tree belong in LT_objs, not LT_deps, because
they are contributing actual content to be included in the resulting
library; they are not library dependencies of the output of this module.

Change-Id: I5292718a5494710d166043fd08ad07269ff9fdf2