glibc: Disable obsolete libcrypt implementation

I've not bothered to write an explanation for --disable-crypt because it
will likely be the default of Glibc-2.38, then we may drop it from the
command lines.

chapter05/glibc.xml

@@ -91,6 +91,7 @@ cd       build</userinput></screen>
       --build=$(../scripts/config.guess) \
       --enable-kernel=&min-kernel;               \
       --with-headers=$LFS/usr/include    \
+      --disable-crypt                    \
       libc_cv_slibdir=/usr/lib</userinput></screen>
 
     <variablelist>