Use more upstream NetBSD, and update those things that were already NetBSD.
Note that unlike bionic, the upstream-netbsd directory isn't pristine; we have
changes marked by __ANDROID__.
Bug: 16493461
Change-Id: I99762bfe02caa0945ea4a184670888a4b5435a1d
uid_from_user doesn't need to cope with numeric ids in the BSD code
like it did with the old Android code; the caller now handles those.
Also explain what SUPPORT_DOT is for.
Change-Id: I185c9f02b7039795069aa30545563b8a6ef54cd5
