[cfe-dev] Add -fno-plt,-fplt to ignored flags

[Joerg Sonnenberger via cfe-dev]

On Fri, Jul 07, 2017 at 07:32:00AM -0400, Jordan Glover via cfe-dev wrote:
> In GCC there is a -fno-plt [1] flag not implemented in Clang which results in compilation failure:
> clang-4.0: error: unknown argument: '-fno-plt'

Can you please slap whoever decided to use a random new GCC flag without
checking for its existance first?

I have seen no evidence of this flag used in the wild so far, so I'm
quite reluctant to accept this change.

Joerg