Hi all,

This is another one of those std::swap patches, this time I was in the combine neighbourhood

Bootstrapped on x86_64 and tested on aarch64.
Precedents suggest these changes are considered obvious.
So I'll commit this in a couple of days unless someone objects.

Thanks,
Kyrill

2015-04-27  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * combine.c (simplify_if_then_else): Use std::swap instead
     of manually swapping.
     (known_cond): Likewise.
     (simplify_comparison): Likewise.