[libstdc++] Add brief documentation narrative for GDB pretty-printers. Add links to GDB wiki/manual

[Phil Muldoon]

This patchlet adds a pointer to the GDB wiki, and additionally the GDB 
manual for information about using STL pretty printing support in GDB.

Additionally,  we updated the GDB wiki STLSupport page with some 
redacted text from mailing lists so the information is one place, 
editable and current. We can add any further tricks and tips there.

I tested this with the make doc-html target.

Ok?

Cheers,

Phil

ChangeLog

2009-10-05  Phil Muldoon <pmuldoon@redhat.com>

     * doc/xml/manual/debug.xml: Add narrative for GDB Python pretty
     printers.  Add links to GDB wiki/online manual

--

Index: libstdc++-v3/doc/xml/manual/debug.xml
===================================================================
--- libstdc++-v3/doc/xml/manual/debug.xml    (revision 152442)
+++ libstdc++-v3/doc/xml/manual/debug.xml    (working copy)
@@ -217,6 +217,20 @@
     set print demangle on
     set demangle-style gnu-v3
</programlisting>
+
+<para>
+  GDB 7.0 will include support for writing pretty-printers in Python.
+  A library of printers for STL classes already exists within the
+  libstdc++ svn repository.  For information on enabling these printers,
+  and for other GDB STL support options: please see
+ <ulink url="http://sourceware.org/gdb/wiki/STLSupport"> "GDB Support
+  for STL" </ulink> in the GDB wiki.  Additionally, in-depth
+  documentation and discussion of this feature can be found in the GDB
+  manual.  Please see:
+ <ulink 
url="http://sourceware.org/gdb/current/onlinedocs//gdb_24.html#SEC260">
+  "23.2.2.6 Pretty Printing" </ulink>
+</para>
+
</sect2>

<sect2 id="debug.exceptions">