Bug 853908 email: point where to find codepages parts not in protocol

(Gaia patch that matches [gelam pull 156](https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/156))

activesync/codepages is split across two build layers, as part of the change for 852710. However, for account setup where there is not an autoconfig match, activesync/protocol is loaded by itself in accountcommon.js. Since the layer that has activesync/protocol does not have all of activesync/codepagse in it, the location of the other parts of activesync/codepages needs to be configured. This patch addresses that issue.

Tested on a non-autoconfig account, and code scanned for any other activesync side loading. This was the only one that was missed as part of 852710.