Deprecate libnsl by default (only shared library will be

Deprecate libnsl by default (only shared library will be
build for backward compatibility, no linking possible) and disable building
of libnss_compat, libnss_nis and libnss_nisplus, except --enable-obsolete-nsl
option is given to configure.

        * config.h.in: Add LINK_OBSOLETE_NSL.
        * config.make.in: Add build-obsolete-nsl.
        * configure.ac: Add obsolete-nsl option.
        * include/libc-symbols.h: Define libnsl_hidden_nolink_def.
        * include/rpcsvc/yp.h: Add missing functions as libnsl_hidden_proto.
        * include/rpcsvc/nislib.h: Likewise.
        * include/rpcsvc/ypclnt.h: Likewise.
        * manual/install.texi: Document --enable-obsolete-nsl.
        * nis/Makefile: Build only libnsl by default (add build-obsolete-nsl).
        * nis/nis_add.c: Replace libnsl_hidden_def with
        libnsl_hidden_nolink_def.
        * nis/nis_addmember.c: Likewise.
        * nis/nis_call.c: Likewise.
        * nis/nis_clone_obj.c: Likewise.
        * nis/nis_defaults.c: Likeise.
        * nis/nis_domain_of_r.c: Likewise.
        * nis/nis_error.c: Likewise.
        * nis/nis_file.c: Likewise.
        * nis/nis_free.c: Likewise.
        * nis_local_names.c: Likewise.
        * nis/nis_lookup.c: Likewise.
        * nis/nis_modify.c: Likewise.
        * nis/nis_print.c: Likewise.
        * nis/nis_remove.c: Likewise.
        * nis/nis_table.c: Likewise.
        * nis/nis_util.c: Likewise.
        * nis/nis_xdr.c: Likewise.
        * nis/yp_xdr.c: Likewise.
        * nis/ypclnt.c: Likewise.
        * nis/ypupdate_xdr.c: Likewise.
        * nis/nis_checkpoint.c: Add libnsl_hidden_nolink_def to all functions.
        * nis/nis_clone_dir.c: Likewise.
        * nis/nis_clone_res.c: Likewise.
        * nis/nis_creategroup.c: Likewise.
        * nis/nis_destroygroup.c: Likewise.
        * nis/nis_domain_of.c: Likewise.
        * nis/nis_getservlist.c: Likewise.
        * nis/nis_ismember.c: Likewise.
        * nis/nis_mkdir.c: Likewise.
        * nis/nis_ping.c: Likewise.
        * nis/nis_print_group_entry.c: Likewise.
        * nis/nis_removemember.c: Likewise.
        * nis/nis_rmdir.c: Likewise.
        * nis/nis_server.c: Likewise.
        * nis/nis_subr.c: Likewise.
        * nis/nis_verifygroup.c: Likewise.

Signed-off-by: Thorsten Kukuk <kukuk@suse.com>