zero index dynamic tls relocs generated for the GOT. Tidy code.
Set "relocation" to 1 on DTPMOD32 relocs. Optimize HA adjustment.
* elf64-ppc.c (ppc64_elf_relocate_section): Likewise.
* ld-powerpc/tlsso.r: Adjust for corrected zero symbol index relocs.
* ld-powerpc/tlsso32.r: Likewise.