Add support for the Rust language

Add support for the Rust language

This patch adds support for the Rust language.

2016-05-17  Tom Tromey  <tom@tromey.com>
	    Manish Goregaokar <manishsmail@gmail.com>

	* symtab.c (symbol_find_demangled_name): Handle Rust.
	* symfile.c (init_filename_language_table): Treat ".rs" as Rust.
	* std-operator.def (STRUCTOP_ANONYMOUS, OP_RUST_ARRAY): New
	constants.
	* rust-lang.h: New file.
	* rust-lang.c: New file.
	* rust-exp.y: New file.
	* dwarf2read.c (read_file_scope): Add Rust producer sniffing.
	(dwarf2_compute_name, read_func_scope, read_structure_type)
	(read_base_type, read_subrange_type, set_cu_language)
	(new_symbol_full, determine_prefix): Handle Rust.
	* defs.h (enum language) <language_rust>: New constant.
	* Makefile.in (SFILES): Add rust-exp.y, rust-lang.c.
	(COMMON_OBS): Add rust-exp.o, rust-lang.o.

2016-05-17  Tom Tromey  <tom@tromey.com>

	* gdb.base/default.exp (set language): Add rust.