First stab at getting namespaces working with PPH. This change will

First stab at getting namespaces working with PPH.  This change will
put top-level namespaces into the global namespace.  It does not,
however, appear to their members in any place useful.

Some tuning of tracing output.

Index: gcc/cp/ChangeLog.pph

2011-04-18  Lawrence Crowl <crowl@google.com>

	* pph.c (pth_save_identifiers): Fix FIXME comment.
        (pph_add_names_to_namespace): Add contained namespaces to scope as
	well as regular symbols.
	* pph-streamer.c (enum pph_trace_type): Add a trace for refs.
        (pph_stream_trace): Add the ref printing.  Reduce bulk of trace
	messages.  Filter off uninteresting traces, primarily traces of null
	pointers.
	(pph_stream_trace_tree): Convert ref_p to trace value.
	* pph-streamer.h: Adjust flag_pph_tracer comparisons for better traces.
	(pph_stream_trace_tree): Add ref_p parameter.  Propogate such
	parameters at all call sites.
        (pph_output_tree_lst): New.  Like pph_output_tree, but for list and
	chain contexts.
	(pph_stream_write_tree): The callback is auxillary.
	(pph_output_chain_filtered): Call pph_output_tree_lst.

Index: libcpp/ChangeLog.pph

2011-04-18  Lawrence Crowl  <crowl@google.com>

	* init.c: Fix spelling in comment.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/pph@172690 138bc75d-0d04-0410-961f-82ee72b054a4