bfd/

bfd/
	* elf.c (_bfd_elf_fixup_group_sections): New function, split out from..
	(_bfd_elf_copy_private_header_data): ..here.
	* elflink.c (_bfd_elf_size_group_sections): New function.
	(bfd_elf_size_dynamic_sections): Call it.
	* elf-bfd.h (_bfd_elf_size_group_sections): Declare.
	(_bfd_elf_fixup_group_sections): Declare.
ld/
	* ldlang.c (unique_section_p): Add os param.  Allow group
	sections to match /DISCARD/.  Update all callers.
	* emultempl/genelf.em (gld${EMULATION_NAME}_before_allocation): New.
	(LDEMUL_BEFORE_ALLOCATION): Define.
ld/testsuite/
	* ld-elf/group.ld: Discard .dropme sections.
	* ld-elf/group10.d, * ld-elf/group10.s: New test.