glibc: Add enable-obsolete-nsl configure option

With glibc 2.26, the name service modules, libnss_nis, libnss_nisplus,
and libnss_compat, are deprecated, and will not be built or installed by
default.

We still require libnss_nis.so, because we use nis for
passwd and shadow in /etc/nsswitch.conf-

Add

    --enable-obsolete-nsl

to build and install the obsolete libnsl library and
depending NSS modules.

glibc.be0

@@ -50,6 +50,7 @@ mee_configure() {
         --disable-profile \
         --enable-add-ons \
         --enable-obsolete-rpc \
+	--enable-obsolete-nsl \
         --enable-kernel=4.4.34
 }