ipa-getkeytab: add option to discover servers using DNS SRV

The basic flow is:

- If server is provided by the user then use it
- If server the magic value '_srv', check for _ldap._tcp SRV records for
  the domain in /etc/ipa/default.conf
- If no servers are found use the server from default.conf

https://pagure.io/freeipa/issue/8478

Signed-off-by: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

client/Makefile.am

@@ -58,6 +58,7 @@ ipa_getkeytab_LDADD = 		\
 	$(SASL_LIBS)		\
 	$(POPT_LIBS)		\
 	$(LIBINTL_LIBS)         \
+	$(RESOLV_LIBS)		\
 	$(INI_LIBS)		\
 	$(NULL)