Sync libiberty sources with GCC.

Sync libiberty sources with GCC.

	PR demangler/70909
	PR demangler/67264
	* cp-demangle.c: Fix endless recursion. Pass
	struct demangle_component as non const.
	(d_make_empty): Initialize variable.
	(d_print_comp_inner): Limit recursion.
	(d_print_comp): Decrement variable.
	* cp-demint.c (cplus_demangle_fill_component): Initialize
	variable.
	(cplus_demangle_fill_builtin_type): Likewise.
	(cplus_demangle_fill_operator): Likewise.
	* testsuite/demangle-expected: Add tests.