[AArch64] Also puts value in place for R_AARCH64_RELATIVE

[Jiong Wang]

When handling absolute relocations for global symbols bind within the
shared object, AArch64 will generate one dynamic RELATIVE relocation,
but won't apply the value for this absolution relocations at static
linking stage. This is different from AArch64 gold linker and x86-64.

I fell this is not a bug as AArch64 is RELA, there is only guarantee
that relocation addend is placed in the relocation entry.  But some
system softwares originally writen for x86-64 might assume AArch64
bfd linker gets the same behavior as x86-64, then they could take
advantage of this buy skipping those RELATIVE dynamic relocations
if the load address is the same as the static linking address.

This patch makes AArch64 BFD linker applies absolution relocations at
static linking stage for scenario described above.  Meanwhile I noticed
old AArch64 android loader has a bug (PR19163) which relies on current
linker behavior as a workaround, so the same option --no-apply-dynamic-relocs
added.

bfd/
   * bfd-in.h (bfd_elf64_aarch64_set_options): Update prototype.
   * bfd-in2.h (bfd_elf64_aarch64_set_options): Likewise.
   * elfnn-aarch64.c (bfd_elfNN_aarch64_set_options): Initialize
   no_apply_dynamic_relocs.
   (elfNN_aarch64_final_link_relocate): Apply absolute relocations even though
   dynamic relocations generated.

ld/
   * emultempl/aarch64elf.em (no-apply-dynamic-relocs): New option.
   * testsuite/ld-aarch64/rela-abs-relative.s: New test source.
   * testsuite/ld-aarch64/rela-abs-relative.d: New expected result.
   * testsuite/ld-aarch64/rela-abs-relative-be.d: Likewise for big-endian.
   * estsuite/ld-aarch64/rela-abs-relative-opt.d: Likewise, but enable new
   option.

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