Force the AArch64 linker backend to refuse to link when it encounters unresoleable...

Force the AArch64 linker backend to refuse to link when it encounters unresoleable relocations.

	* reloc.c (enum bfd_reloc_status): Start values at 2.
	* bfd-in2.h: Regenerate.
	* elfnn-aarch64.c (aarch64_relocate): Invert sense of function, so
	that a TRUE return indicates success.  Compare the result of
	calling _bfd_aarch64_elf_put_addend against bfd_reloc_ok.
	(build_one_stub): Change sense of tests against aarch64_relocate
	return value.
	(elfNN_aarch64_tls_relax): Return bfd_reloc_notsupported, rather
	than FALSE, when an error is detected.
	(elfNN_aarch64_final_link_relocate): Likewise.

	* testsuite/ld-aarch64/pcrel_pic_defined.d: Expect errors not
	warnings.  Expect errors about unsupported relocations.
	* testsuite/ld-aarch64/pcrel_pic_undefined.d: Likewise.