RFA: Fix MIPS TLS assertion failure

[Eric Christopher]

>
> The patch below fixes this.  Tested on mips-linux-gnu.  OK to install?
>
> Richard
>
>
> bfd/
> 	* elfxx-mips.c (mips_elf_initialize_tls_index): If a TLS symbol
> 	has already been assigned a GOT index, copy that index to the
> 	current hash table entry.
>
> ld/testsuite/
> 	* ld-mips-elf/tls-hidden2a.s, ld-mips-elf/tls-hidden2b.s,
> 	* ld/testsuite/ld-mips-elf/tls-hidden2.d,
> 	* ld/testsuite/ld-mips-elf/tls-hidden2-got.d: New test.
> 	* ld-mips-elf/mips-elf.exp: Run it.

OK.

-eric