No bug - Add some old committer emails to mailmap. DONTBUILD

I happened to notice this when trying to find my oldest commit.

Differential Revision: https://phabricator.services.mozilla.com/D217202

.mailmap

@@ -2,3 +2,6 @@ Andreas Tolfsen <[email protected]> <[email protected]>
 Nika Layzell <[email protected]> <[email protected]>
 Alex Thayer <[email protected]>
 Beth Rennie <[email protected]> <[email protected]>
+Emilio Cobos Álvarez <[email protected]> <[email protected]>
+Emilio Cobos Álvarez <[email protected]> <[email protected]>
+Emilio Cobos Álvarez <[email protected]> <[email protected]>