Remove outdated text regarding test timing in libtool

was r11625.

chapter06/libtool.xml

@@ -49,7 +49,7 @@
 
 <screen><userinput remap="make">make</userinput></screen>
 
-    <para>为了测试编译结果（需要约 11.0 SBU），执行：</para>
+    <para>为了测试编译结果，执行：</para>
 
 <screen><userinput remap="test">make check</userinput></screen>