[Patch, MIPS] Add Octeon3 support

[Matthew Fortune]

> Updating octeon3 in doc/c-mips.texi.
> 
> Please review the patch and let us know if there should be any
> further modifications.

Hi Naveen,

Sorry for the delay in responding. I can't approve the patch but
FWIW it looks OK except for below...

Please could you add an octeon3 value for .MIPS.abiflags as
AFP_EXT_OCTEON3. This should be used in both bfd_mips_isa_ext
and print_mips_isa_ext for elfxx-mips.c and print_mips_isa_ext
in readelf.c. I.e. all the places which AFP_EXT_OCTEON2 is used.

Thanks,
Matthew