xpmem: fix mapping of attachment and segment

* Mapping attached part of segment is done at attach time instead of
  make time to work with runtimes (e.g. OpenMPI) xpmem_make-ing the
  entire user-space
* Mapping attached part of segment at attach time can be turned off by
  specifying xpmem_remote_on_demand in kernel argument
* Mapping attachment chooses appropriate page-sizes, i.e., largest
  allowed by memory range and segment page boundary

Fixes: a8696d8 "xpmem: Support large page attachment"
Change-Id: I44663865204036520e5f62fe22b9134ee4629f9b

test/issues/1473/xpmem_make01.sh.in

@@ -0,0 +1,8 @@
+#!/usr/bin/bash
+
+. @CMAKE_INSTALL_PREFIX@/bin/common.sh
+
+@WITH_MCK@/bin/mcexec @CMAKE_INSTALL_PREFIX@/bin/xpmem_make01
+ret=$?
+
+exit $ret