Fix up @martinhath's mailmap entry

Author: Martin Hafskjold Thoresen

.mailmap

@@ -139,6 +139,7 @@ Margaret Meyerhofer <mmeyerho@andrew.cmu.edu> <mmeyerho@andrew>
 Mark Sinclair <mark.edward.x@gmail.com>
 Mark Sinclair <mark.edward.x@gmail.com> =Mark Sinclair <=125axel125@gmail.com>
 Markus Westerlind <marwes91@gmail.com> Markus <marwes91@gmail.com>
+Martin Hafskjold Thoresen <martinhath@gmail.com>
 Matej Lach <matej.lach@gmail.com> Matej Ľach <matej.lach@gmail.com>
 Matt Brubeck <mbrubeck@limpet.net> <mbrubeck@cs.hmc.edu>
 Matthew Auld <matthew.auld@intel.com>