bad definition of IDENTIFIER_GLOBAL_VALUE

[Per Bothner <bothner at cygnus dot com>]

The macros IDENTIFIER_GLOBAL_VALUE and IDENTIFIER_NAMESPACE_VALUE
call binding_for_name, which creates a new binding, if there is none.

This is inefficient, since it creates new CPLUS_BINDINGs
unnecessarily.  Most uses of IDENTIFIER_GLOBAL_VALUE are in
an rvalue context, where creating a new binding is useless.

Worse, print_lang_identifier invokes IDENTIFIER_GLOBAL_VALUE.
This means that calling debug_tree from the debugger may
invoke make_node.  This means that debugging cc1plus is no
longer determinate, but the address of nodes depends on
whatever previous nodes have been printed using debug_tree.
That is why it is totally unacceptable for debug_tree to
allocate any memory.  (The only exception is buffers allocated
by printf, which we cannot control, but at least normally
only happens once.)

	--Per Bothner
Cygnus Solutions     bothner@cygnus.com     http://www.cygnus.com/~bothner