* ldemul.c (ldemul_place_orphan): Add "constraint" param.

	* ldemul.c (ldemul_place_orphan): Add "constraint" param.
	* ldemul.h (ldemul_place_orphan): Update prototype.
	(struct ld_emulation_xfer_struct <place_orphan>): Likewise add param.
	* ldlang.c (unique_section_p): Make static.
	(lang_output_section_statement_lookup): Optimise creation of SPECIAL
	sections.
	(lang_insert_orphan): Add "constraint" param.  Pass to
	lang_enter_output_section_statement.
	(init_os): Don't use an existing bfd section for SPECIAL sections.
	(lang_place_orphans): Don't rename unique output sections, instead
	mark their output section statements SPECIAL.
	* ldlang.h (lang_insert_orphan): Update prototype.
	(unique_section_p): Delete.
	* emultempl/beos.em (place_orphan): Add "constraint" param.
	* emultempl/elf32.em (place_orphan): Likewise.  Don't match existing
	output sections if set.
	* emultempl/pe.em (place_orphan): Likewise.
	* emultempl/pep.em (place_orphan): Likewise.
	* emultempl/mmo.em (mmo_place_orphan): Update.
	* emultempl/spuelf.em (spu_place_special_section): Update.