Allocate abbrev_table with new

Allocate abbrev_table with new

This changes dwarf2read.c to allocate abbrev tables using "new", and
then updates the users.

This version of the patch incorporates the changes that Simon
implemented.  These changes simplify the ownership rules for abbrev
tables.

2018-01-17  Tom Tromey  <tom@tromey.com>
	    Simon Marchi  <simon.marchi@ericsson.com>

	* dwarf2read.c (struct dwarf2_cu) <abbrev_table>: Remove.
	(struct die_reader_specs) <abbrev_table>: New member.
	(struct abbrev_table): Add constructor.
	<alloc_abbrev, add_abbrev, lookup_abbrev>: Declare.
	<abbrev_obstack>: Now an auto_obstack.
	(abbrev_table_up): New typedef.
	(init_cu_die_reader): Add abbrev_table parameter.
	(read_cutu_die_from_dwo): Remove abbrev_table_provided parameter.
	Add result_dwo_abbrev_table.
	(init_tu_and_read_dwo_dies, init_cutu_and_read_dies)
	(init_cutu_and_read_dies_no_follow, build_type_psymtabs_1):
	Update.
	(peek_die_abbrev): Take die_reader_specs, not dwarf_cu as
	parameter.
	(skip_children): Update.
	(abbrev_table::alloc_abbrev): Rename from
	abbrev_table_alloc_abbrev.
	(abbrev_table::add_abbrev): Rename from abbrev_table_add_abbrev.
	(abbrev_table::lookup_abbrev): Rename from
	abbrev_table_lookup_abbrev.
	(abbrev_table_read_table): Return abbrev_table_up.
	(abbrev_table_free, abbrev_table_free_cleanup)
	(dwarf2_read_abbrevs, dwarf2_free_abbrev_table): Remove.
	(load_partial_dies): Update.