use export_exlib_phases

Change-Id: I9717de9c997596c67ed01e22b7786a7884c5ff0a
xapian-core: ::ingmar -> ::arbor
repository_mask.conf: remove obsolete xapian-core mask
Version bump to mr-1.20140831.1
notmuch: Test was renamed

Renamed upstream since a755c9d6, Jan 9 2014.
Did no one run notmuch tests since then?
app-arch/dpkg: add ~arm to PLATFORMS

Change-Id: I11b3cc6fbf7e9a36be590d3c5c9c9fb28dfb351a