sparc TPOFF handling in GOLD

[David Miller]

Ian, I figured out why I was using the relative reloc
emitters for relocations other than R_SPARC_RELATIVE.

It seems to be for an issue with TPOFF{32,64} handling.

For example, when we have an IE TLS relocation for a local symbol, the
TPOFF{32,64} relocation pointing to the GOT entry needs to have an
addend with value:

	value - tls_segment()->vaddr();

This is needed because the dynamic linker sets the relocation using:

	*reloc_addr = sym->st_value - sym_map->l_tls_offset
		+ reloc->r_addend;

Compare to i386 which, lacking addends, goes:

	*reloc_addr += map->l_tls_offset - sym->st_value;

x86_64 uses addends and seems to compute the TPOFF64 relocation
similar to sparc, so I wonder how it is working there?

Anyways, way back when writing the Sparc GOLD backend I couldn't
figure out any way to get that TPOFF{32,64} addend set correctly other
than to use the relative reloc trick since that triggers the logic in
Output_reloc::write() which goes:

  addend = this->rel_.symbol_value(addend);

But now that we emit DT_RELACOUNT in the dynamic section, this trick
no longer works.

Maybe I'm missing something obvious here that can be used to make this
work?  Perhaps I need to use a target specific relocation?

Thanks!