Move ELF relocation check after lang_gc_sections

Move ELF relocation check after lang_gc_sections

Move ELF relocation check after lang_gc_sections so that all the
reference counting code for plt and got relocs can be removed.  This
only affects ELF targets which check relocations after opening all
input file.

	* ldlang.c (lang_check_relocs): New function.
	(lang_process): Call lang_check_relocs after lang_gc_sections.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Don't
	call _bfd_elf_link_check_relocs here.