* script-sections.h: Include <list>.

	* script-sections.h: Include <list>.
	(class Script_sections): Change Sections_elements from std::vector
	to std::list.  Typedef public Elements_iterator.  Add
	orphan_section_placement_, data_segment_align_start_, and
	saw_data_segment_align_ fields.  Remove data_segment_align_index_
	field.
	* script-sections.cc (class Orphan_section_placement): New class.
	(class Sections_element): Add virtual functions is_relro and
	orphan_section_init.  Remove virtual function place_orphan_here.
	(class Output_section_definition): Add is_relro and
	orphan_section_init.  Remove place_orphan_here.
	(class Orphan_output_section): Likewise.
	(Script_sections::Script_sections): Update for field changes.
	(Script_sections::data_segment_align): Set saw_data_segment_align_
	and data_segment_align_start_, not data_segment_align_index.
	(Script_sections::data_segment_relro_end): Check
	saw_data_segment_align_.  Use data_segment_align_start_ rather
	than data_segment_align_index_.
	(Script_sections::place_orphan): Rewrite to use
	Orphan_section_placement.