LoongArch: ld: Simplify inserting IRELATIVE relocations to .rela.dyn

LoongArch: ld: Simplify inserting IRELATIVE relocations to .rela.dyn

In LoongArch, the R_LARCH_IRELATIVE relocations for local ifunc symbols are
in .rela.dyn. Before, this is done by loongarch_elf_finish_dynamic_sections.
But this function is called after elf_link_sort_relocs, it need to find a
null slot to insert IRELATIVE relocation.

Now, it is processed by elf_loongarch_output_arch_local_syms before
elf_link_sort_relocs, just need to call loongarch_elf_append_rela to
insert IRELATIVE relocation.

bfd/ChangeLog:

	* elfnn-loongarch.c (elfNN_allocate_local_ifunc_dynrelocs): Return
	type change to int.
	(loongarch_elf_size_dynamic_sections): Delete (void *).
	(loongarch_elf_finish_dynamic_symbol): Use loongarch_elf_append_rela
	insert IRELATIVE relocation to .rela.dyn.
	(elfNN_loongarch_finish_local_dynamic_symbol): Return type change to
	int.
	(loongarch_elf_finish_dynamic_sections): Delete process of local
	ifunc symbols.
	(elf_backend_output_arch_local_syms): New.

ld/ChangeLog:

	* testsuite/ld-loongarch-elf/local-ifunc-reloc.d: Regenerated.