Fix links against /usr/lib/libc.so on IRIX

[Eric Christopher]

> bfd/
> 	* elfxx-mips.c (MIPS_ELF_OPTIONS_SECTION_NAME_P): New macro.
> 	(_bfd_mips_elf_section_from_shdr): Use it to check for recognized
> 	SHT_MIPS_OPTIONS names.  Allow all sections with unrecognised
> 	section flags.
> 	(_bfd_mips_elf_fake_sections): Use MIPS_ELF_OPTIONS_SECTION_NAME_P
> 	to check for SHT_MIPS_OPTIONS sections.
> 	(_bfd_mips_elf_set_section_contents): Likewise.

OK.

-eric