Before, SearchableInfo read and cached the localized
searchable description, which meant that it was not updated
on locale changes. Now SearchableInfo only holds the resource
ID.
SearchableInfo is a new API in Froyo, so it's ok to change.
Part of http://b/issue?id=2175247
Change-Id: I1898f7895b9172f58419d906ad741cb7dd1e7252