or1k: Implement relocation R_OR1K_GOT_AHI16 for gotha()

The gotha() relocation mnemonic will be outputted by OpenRISC GCC when
using the -mcmodel=large option.  This relocation is used along with
got() to generate 32-bit GOT offsets.  This increases the previous GOT
offset limit from the previous 16-bit (64K) limit.

This is needed on large binaries where the GOT grows larger than 64k.

bfd/ChangeLog:

	PR 21464
	* bfd-in2.h: Add BFD_RELOC_OR1K_GOT_AHI16 relocation.
	* elf32-or1k.c (or1k_elf_howto_table, or1k_reloc_map): Likewise.
	(or1k_final_link_relocate, or1k_elf_relocate_section,
	or1k_elf_check_relocs): Likewise.
	* libbfd.h (bfd_reloc_code_real_names): Likewise.
	* reloc.c: Likewise.

cpu/ChangeLog:

	PR 21464
	* or1k.opc (or1k_imm16_relocs, parse_reloc): Define parse logic
	for gotha() relocation.

include/ChangeLog:

	PR 21464
	* elf/or1k.h (elf_or1k_reloc_type): Define R_OR1K_GOT_AHI16 number.

opcodes/ChangeLog:

	PR 21464
	* or1k-asm.c: Regenerate.

gas/ChangeLog:

	PR 21464
	* testsuite/gas/or1k/reloc-1.s: Add test for new relocation.
	* testsuite/gas/or1k/reloc-1.d: Add test result for new
	relocation.

Cc: Giulio Benetti <giulio.benetti@benettiengineering.com>

fixup reloc, add tests