[PATCH] Support 'exclude' in objcopy --set-section-flags

[Nick Clifton]

Hi Fangrui,

>> --set-section-flags .foo= => clear SHF_EXCLUDE
>> --set-section-flags .foo=exclude => set SHF_EXCLUDE
> 
> Ping :)

Approved and applied - mostly.  You also had an undocumented
change to _bfd_elf_init_private_section_data() which would
remove the SHF_EXCLUDE bit from sections with OS or PROC
specific flags.  This breaks several linker tests, and seemed
to be unrelated to the main purpose of the patch, so I discarded
it.

Cheers
  Nick