Mudflap cleanup

[Jan Hubicka]

> Hi,
> I sent this change already together with the patch to switch into SSA as I
> convinced myself I can't split it without introducing temporary regressions.
> This was wrong, as it is rather easy ;)

Just for a record, since this patch is part of the IPA-SSA patch
approved by Roger, it no longer needs reviewing.
I've committed it separately from the rest of IPA-SSA patch to simplify
possible identification of the guilty patch in the future.

Honza