merge from gcc

merge from gcc

libiberty/
	PR debug/49408
	* cp-demangle.c (d_print_comp): Suppress argument list for function
	references by the '&' unary operator.  Keep also already processed
	variant without the argument list.  Suppress argument list types for
	function call used in an expression.
	* testsuite/demangle-expected: Fix excessive argument list types in
	`test for typed function in decltype'.  New testcase for no argument
	list types printed.  3 new testcases for function references by the
	'&' unary operator..