This will eliminate the need for automake to build these files
for each backend that consumes LDAP and KRB5 functionality
(currently 'ldap', 'krb5' and 'ipa'; soon to include
'ad')
This will speed up builds slightly, since they won't need to compile
each of these files three times and it will make maintaining the list of
files in Makefile.am simpler, since we won't need to remember to update
three different places.
Also, if you're wondering, I left the src/util/sss_ldap.c and
src/util/sss_krb5.c off the list because they are sometimes included
where the rest of the routines are not (such as in the ldap_child and
krb5_child processes).