stripping: add libnss_*.so* into online_usrlib

Glibc loads these "NSS modules" (see man 5 nss) on startup.  This is
implemented with something like dlopen() so "ldd" won't show them up.
So they should be considered "online" here.

Without this addition, overwriting libnss_files-2.33.so reproducibly
triggers a crash during jhalfs runs where stripping is enabled.  In
manual builds, it reproducibly triggers a crash exiting from chroot.

After this change I reran stripping 5 times and there was no crash
observed.

chapter01/changelog.xml

@@ -43,6 +43,16 @@
     appropriate for the entry or if needed the entire day's listitem.
     -->
 
+    <listitem>
+      <para>2021-07-27</para>
+      <itemizedlist>
+        <listitem>
+          <para>[xry111] - Use workaround for Glibc NSS modules during
+          stripping, to prevent bash from crash.</para>
+        </listitem>
+      </itemizedlist>
+    </listitem>
+
     <listitem>
       <para>2021-07-26</para>
       <itemizedlist>

chapter08/strippingagain.xml

@@ -62,7 +62,8 @@ online_usrbin="bash find strip"
 online_usrlib="libbfd-&binutils-version;.so libdl-&glibc-version;.so
                libhistory.so.&readline-version; libncursesw.so.&ncurses-version;
                libm-&glibc-version;.so libreadline.so.&readline-version;
-               libz.so.&zlib-version;"
+               libz.so.&zlib-version;
+               $(cd /usr/lib; find libnss*.so* -type f)"
 
 for BIN in $online_usrbin; do
     cp /usr/bin/$BIN /tmp/$BIN