* dwarf2read.c (dwarf2_read_abbrevs): Return 1 iff we saw any

	* dwarf2read.c (dwarf2_read_abbrevs): Return 1 iff we saw any
	DW_FORM_ref_addr tags.
	(create_comp_unit_tree): Add prototype.  Take an objfile instead
	of a compilation unit.
	(dwarf2_build_psymtabs_hard): Build the compilation unit tree
	as soon as we find an inter-CU reference.  Update call to
	create_comp_unit_tree.
	(dwarf2_find_containing_comp_unit): Don't create the tree here.
	(psymtab_to_symtab_1): Update to support no tree having been built.
	(set_die_type): Likewise.