ia64.c (ia64_attribute_table): Add "common_object" entry.

ia64.c (ia64_attribute_table): Add "common_object" entry.

	* config/ia64/ia64.c (ia64_attribute_table): Add "common_object"
	entry.
	(SECTION_VMS_OVERLAY): Define.
	(ia64_vms_common_object_attribute): Added.  Handle the "common_object"
	attribute.
	(ia64_vms_elf_asm_named_section): Added.  Generate .section pseudo-op
	for common_object.
	(ia64_vms_output_aligned_decl_common): Added.  Generate pseudo-op for
	common_object declarations.
	(ia64_section_type_flags): Set section flag for common_object.
	* config/ia64/ia64-protos.h
	(ia64_vms_output_aligned_decl_common): Declare.
	(ia64_vms_elf_asm_named_section): Declare.

Co-Authored-By: Douglas B Rupp <rupp@gnat.com>
From-SVN: r151148