Support rvalue reference type in parser

Support rvalue reference type in parser

This patch implements correct parsing of C++11 rvalue reference typenames.
This is done in full similarity to the handling of regular references by adding
a '&&' token handling in c-exp.y, defining an rvalue reference type piece, and
implementing a follow type derivation in follow_types().

gdb/ChangeLog

	PR gdb/14441
	* c-exp.y (ptr_operator): Handle the '&&' token in the typename.
	* parse.c (insert_type): Change assert statement.
	(follow_types): Handle rvalue reference types.
	* parser-defs.h (enum type_pieces) <tp_rvalue_reference>: New
	constant.