BFD: Use `bfd_is_abs_symbol' to determine whether a symbol is absolute

BFD: Use `bfd_is_abs_symbol' to determine whether a symbol is absolute

Use `bfd_is_abs_symbol' to determine whether a symbol is absolute,
avoiding a problem with ordinary symbols defined in a linker script
outside an output section definition.  Such symbols have its owning
section set to the absolute section up to the final link phase.  A flag
has been added to the link hash to identify such symbols.  Rather than
checking the flag by hand, use the macro that does it uniformly for all
users.

	bfd/
	* elf32-nds32.c (nds32_elf_relax_loadstore): Use
	`bfd_is_abs_symbol' rather than `bfd_is_abs_section' in checking
	whether the symbol is absolute.
	(nds32_elf_relax_lo12): Likewise.
	* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Likewise.
	(elfNN_aarch64_check_relocs): Likewise.
	* xcofflink.c (xcoff_need_ldrel_p): Likewise.
	(bfd_xcoff_import_symbol): Likewise.
	(xcoff_write_global_symbol): Likewise.