glibc: fix parallel build issue with make-4.4

We only need a one-line change in upstream fix (because we don't use
"make --shuffle").  Add it as a sed for both Chapter 5 and Chapter 8.

Note that the "minimal" sed would be '/MAEKFLAGS :=/s/r/ -r/'.  I
included an additional ')' so it won't modify "-r" again to "- -r".

Tested "make" and "make check" on a x86_64 with -j8 and an arm64 with
-j24.

Link: https://sourceware.org/git/?p=glibc.git;a=commit;h=2d7ed98add14

chapter05/glibc.xml

@@ -64,6 +64,11 @@ esac</userinput></screen>
       </para>
     </note>
 
+    <para>Fix an issue building Glibc with parallel jobs and make-4.4
+    or later:</para>
+
+<screen><userinput remap="pre">sed '/MAKEFLAGS :=/s/)r/) -r/' -i Makerules</userinput></screen>
+
     <para>Some of the Glibc programs use the non-FHS-compliant
     <filename class="directory">/var/db</filename> directory to store their
     runtime data. Apply the following patch to make such programs store their