From: Hugh Dickins <hugh@veritas.com>

I like CONFIG_REGPARM, even when it's forced on: because it's easy to force
off for debugging - easier than editing out scattered fastcalls.  Plus I've
never understood why we make function foo a fastcall, but function bar not.
Remove fastcall directives from rmap.  And fix comment about mremap_moved
race: it only applies to anon pages.