Permit MAP_RENAME and MAP_NORESERVE for now.  These flags should be removed, but at least
Chromium and OpenJDK use MAP_NORESERVE.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271681 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f