Add libsigsegv as an optional dependency of grep.

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11806 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

appendices/dependencies.xml

@@ -1078,7 +1078,7 @@
         <segtitle>&external;</segtitle>
 
         <seglistitem>
-          <seg>Pcre</seg>
+          <seg>Pcre and libsigsegv</seg>
         </seglistitem>
       </segmentedlist>